We detail here some matters arising from the recent paper by Qin et al., Nature 606, pages902–908 (2022). We demonstrate, based on data supplied by Qian et al, and corroborated by theoretical modeling, that one of the central conclusions of the manuscript – namely the behavior of the chirality-induced spin-selectivity (CISS) effect at low temperatures – can actually be consistently interpreted in a different way, which is in fact opposite to the interpretation proposed by Qian et al.

Motivated by the recent success of local electron tunneling into heavy-fermion materials, we study the local electronic structure around a single Kondo hole in an Anderson lattice model and the Fano interference pattern relevant to STM experiments. Within the Gutzwiller method, we find that an intragap bound state exists in the heavy Fermi liquid regime. The energy position of the intragap bound state is dependent on the on-site potential scattering strength in the conduction and f-orbital channels. Within the same method, we derive a new dI/dV formulation, which includes explicitly the renormalization effect due to the f-electron correlation. It is found that the Fano interference gives asymmetric coherent peaks separated by the hybridization gap. The intragap peak structure has a lorenzian shape, and the corresponding dI/dV intensity depends on the energy location of the bound state.

We present tunneling measurements of sub-micron metal/insulator/graphene planar tunnel junctions up to room temperature. We observe a gate independent gap, as previously observed only by low temperature STM[Y. Zhang et al., Nat. Phys. 4, 627 (2008)]. No gap appears at temperatures above 150K, which is four times smaller than the theoretically expected $T_{c}$, from the accepted mean field model[T. O. Wehling et al. Phys. Rev. Lett. 101, 216803 (2008)]. We show that taking into account an additional vibrational effect of out-of-plane phonon soft modes the gap may disappear from the measurements at temperatures much lower than the calculated $T_{c}$.

Through an analysis and modeling of data from various experimental techniques, we present clear evidence for the presence of a hidden-order pseudogap in URu2Si2 in the temperature range 25-17.5 K. Considering fluctuations of the hidden-order energy gap at the transition, we evaluate the effects that gap fluctuations would produce on observables like tunneling conductance, neutron scattering, and nuclear resonance, and relate them to the experimental findings. We show that the transition into the hidden-order phase is likely second order and is preceded by the onset of noncoherent hidden-order fluctuations.

Phase fluctuations in finite thickness layered superconducting films are studied theoretically. The model consists of a set of layers, coupled to each other via a gradient-like term in the phase-only action. It is shown that the effective phase stiffness of the whole system is proportional to its thickness (i.e. the number of individual layers). This result leads to a superconductor-insulator transition and an inverse dependence of $T_c$ on thickness,$T_c\sim d^{-1}$, both in accord with the experimental findings. The relevance to disordered thin films is discussed.

Recently observed tunneling spectra on clean heavy-fermion compounds show a lattice periodic Fano line shape similar to what is observed in the case of tunneling to a Kondo ion adsorbed at the surface. We show that the translation symmetry of a clean surface in the case of weakly correlated metals leads to a tunneling spectrum which shows a hybridization gap but does not have a Fano line shape. By contrast, in a strongly correlated heavy-fermion metal the heavy quasiparticle states will be broadened by interaction effects. The hybridization gap is completely filled in this way, and an ideal Fano line shape of width ∼2TK results. In addition, we discuss the possible influence of the tunneling tip on the surface, in (i) leading to additional broadening of the Fano line and (ii) enhancing the hybridization locally, hence adding to the impurity type behavior. The latter effects depend on the tip-surface distance.

In a two-qubit system the coupling with an environment considerably affects the entanglement dynamics, usually leads to the loss of entanglement within a finite time. Since entanglement is a key feature in the application of such systems to quantum information processing, it is highly desirable to find a way to prolonging its lifetime. We present a simple model of an interacting two-qubit system in the presence of a thermal Markovian environment. The qubits are modeled as interacting spin-$1∕2$ particles in a magnetic field and the environment is limited to inducing single spin-flip events. A simple scheme allows us to calculate the relaxation rates for all processes. We show that the relaxation dynamics of the most entangled state exhibit critical slowing down as a function of the magnetic field, where the relaxation rate changes from exponentially small values to finite values in the zero-temperature limit. We study the effect of temperature and magnetic field on all the other relaxation rates and find that they exhibit unusual properties, such as nonmonotonic dependence on temperature and a discontinuity as a function of magnetic field. In addition, a simple scheme to include non-Markovian effects is presented and applied to the two-qubit model. We find that the relaxation rates exhibit a sharp, cusplike resonant structure as a function of the environment memory time, and that for long memory times all the different relaxation rates merge into a single one.

We introduce the concept of information compressibility, KI, which measures the relative change of number of available microstates of an open system in response to an energy variation. We then prove that at the time in which the system reaches a steady state, the second and third time derivatives of the information entropy are proportional to the corresponding time derivatives of the energy, the proportionality constant being KI. We argue that if two steady states with different but same-sign KI are dynamically connected in a non-adiabatic way it takes a longer time to reach the state with compressibility closer to zero than the reverse. We also show analytically that for a two-level system in contact with external baths, the information compressibility is inversely proportional to the temperature measured at any given time by a probe that is coupled to the system, and whose temperature is adjusted so that the system dynamics is minimally perturbed. This concept, that applies to both classical and quantum open systems, thus provides insight into the properties of non-equilibrium steady states.

We have performed first order reversal curve measurements of the temperature-driven metalinsulator transition in VO2 thin films, which enable quantitative analysis of the hysteresis behavior. An unexpected tail-like feature in the contour plot of the reversal curve distribution indicates the existence of metallic domains, even at temperatures below the closing of the hysteresis. These domains interact with the surrounding medium and change the reversal path relative to a path from a fully insulating state. With this in mind, and assuming that such interaction persist through the entire phase transition, we develop a model where the driving force (or energy barrier) in charge of opening a hysteresis in VO2 are inter-domain interactions. This model is intrinsically different from the Preisach model usually used to describe hysteresis; given that it looks for the microscopic origin of the hysteresis, and provides physical parameters to characterize it.

The theory of open quantum systems is used to study the local temperature and heat currents in metallic nanowires connected to leads at different temperatures. We show that for ballistic wires the local temperature is almost uniform along the wire and Fourier's law is invalid. By gradually increasing disorder, a uniform temperature gradient ensues inside the wire and the thermal current linearly relates to this local temperature gradient, in agreement with Fourier's law. Finally, we demonstrate that while disorder is responsible for the onset of Fourier's law, the non-equilibrium energy distribution function is determined solely by the heat baths.

A generalized theory of open quantum systems combined with mean-field theory is used to study a superconducting wire in contact with thermal baths at different temperatures. It is shown that, depending on the temperature of the colder bath, the temperature of the hotter bath can greatly exceed the equilibrium critical temperature, and still the local temperature in the wire is maintained below the critical temperature and hence the wire remains in the superconducting state. The effects of contact areas and disorder are studied. Finally, an experimental setup is suggested to test our predictions.

The onset of Fourier's law in a one-dimensional quantum system is addressed via a simple model of weakly coupled quantum systems in contact with thermal baths at their edges. Using analytical arguments we show that the crossover from the ballistic (invalid Fourier's law) to diffusive (valid Fourier's law) regimes is characterized by a thermal length scale, which is directly related to the profile of the local temperature. In the same vein, dephasing is shown to give rise to classical Fourier's law, similarly to the onset of Ohm's law in mesoscopic conductors.

Despite its intrinsic non-equilibrium origin, thermoelectricity in nanoscale systems is usually described within a static scattering approach which disregards the dynamical interaction with the thermal baths that maintain energy flow. Using the theory of open quantum systems we show instead that unexpected properties, such as a resonant structure and large sign sensitivity, emerge if the non-equilibrium nature of this problem is considered. Our approach also allows us to define and study a local temperature, which shows hot spots and oscillations along the system according to the coupling of the latter to the electrodes. This demonstrates that Fourier's law – a paradigm of statistical mechanics – is violated at the nanoscale.

Quantum master equations are common tools to describe the dynamics of many-body systems open to an environment. Due to the interaction with the latter, even for the case of noninteracting electrons, the computational cost to solve these equations increases exponentially with the particle number. We propose a simple scheme, which allows to study the dynamics of N noninteracting electrons taking into account both dissipation effects and Fermi statistics, with a computational cost that scales linearly with N. Our method is based on a mapping of the many-body system to a specific set of effective single-particle systems. We provide detailed numerical results showing excellent agreement between the effective single-particle scheme and the exact many-body one, as obtained from studying the dynamics of two different systems. In the first, we study optically-induced currents in quantum rings at zero temperature, and in the second we study a linear chain coupled at its ends to two thermal baths with different (finite) temperatures. In addition, we give an analytical justification for our method, based on an exact averaging over the many-body states of the original master equations.

Recent experimental studies of magnetoresistance in disordered superconducting thin films on the insulating side of the superconductor-insulator transition reveal a huge peak (about 5 orders of magnitude compared with the resistance at the transition). While it may be expected that magnetic field destroys superconductivity, leading to an enhanced resistance, attenuation of the resistance at higher magnetic fields is surprising. We propose a model which accounts for the experimental results in the entire range of magnetic fields, based on the formation of superconducting islands due to fluctuations in the superconducting order parameter amplitude in the disordered sample. At strong magnetic fields, due to Coulomb blockade in these islands, transport is mainly through the normal areas, and thus a decrease is the size and density of the superconducting islands leads to an enhanced conductance and a negative magnetoresistance. As the magnetic field is reduced and the size and density of these islands increase, the conductance is eventually dominated by transport through the superconducting islands and the magnetoresistance changes sign. Numerical calculations show a good qualitative agreement with experimental data.

A model consisting of a mixture of superconducting and quantum links is proposed to describe the integer quantum Hall transition. The quantum links correspond to tunneling of electrons between trajectories trapped in adjacent potential valleys, while the superconducting links mimic the merging of these trajectories once the Fermi energy exceeds the saddle point energy separating the two valleys. The quantum Hall transition in this model corresponds to percolation of the superconducting links. Numerical calculations and scaling analysis using two different approaches yield the critical exponent $\ensuremath{\nu}\ensuremath{\approx}2.4$ and a two-peak conductance distribution at the critical point. The role of quantum coherence is discussed, allowing an interpretation of $\ensuremath{\nu}\ensuremath{\approx}1.3$, found in some experiments, in terms of the percolation critical exponent. The model suggests that the critical behavior of the superconductor-insulator transition (on the insulating side) is in the same universality class as the quantum Hall transition.

The relative intensity of glow peak 5a in the composite glow peak 5 of LiF:Mg,Ti (TLD-100) is very weak following gamma irradiation, and has been estimated at approximately 0.1 of the intensity of peak 5. Typical glow curve analysis using computerised glow curve deconvolution with unconstrained variation of the peak shape parameters, yields values of the relative intensity of glow peak 5a varying from 0 to 15%. Due to the potential of peak 5a to fulfil the criteria of a quasi-tissue-equivalent nanodosemeter which estimates quality factor, considerable efforts have been invested in ancilliary techniques to improve the reliability of the estimation of the intensity of peak 5a. Optical bleaching and thermal annealing techniques were used to obtain single-peak glow curves consisting of peak 4 only and peak 5 only. A multi-stage CGCD protocol was then constructed using these peak shape parameters for peaks 4 and 5, which allows more accurate estimation of the relative intensity of peak 5a. Following 60Co irradiation of ten chips to a dose level of 1 Gy, the technique yields a relative intensity of 0.08 +/- 0.008 (1 SD).