pinecone/core-2020-05-10-deduplication huggingface dataset:
Evolution of electric-field-induced quasibound states and resonances in
  one-dimensional open quantum systems

A comparative analysis of three different time-independent approaches to
studying open quantum structures in uniform electric field $\mathscr{E}$ was
performed using the example of one-dimensional attractive or repulsive
$\delta$-potential and surface that supports the Robin boundary condition. The
three considered methods exploit different properties of the scattering matrix
$S(\mathscr{E};E)$ as a function of energy $E$: its poles, real values, and
zeros of the second derivative of its phase. The essential feature of the
method of zeroing the resolvent, which produces complex energies, is the
unlimited growth of the wave function at infinity, which is, however,
eliminated by the time-dependent interpretation. The real energies at which the
unitary scattering matrix becomes real correspond to the largest possible
distortion, $S=+1$, or its absence at $S=-1$ which in either case leads to the
formation of quasibound states. Depending on their response to increasing
electric intensity, two types of field-induced positive energy quasibound
levels are identified: electron- and hole-like states. Their evolution and
interaction in enlarging field lead ultimately to the coalescence of pairs of
opposite states, with concomitant divergence of the associated dipole moments
in what is construed as an electric breakdown of the structure. The
characteristic features of the coalescence fields and energies are calculated
and the behavior of the levels in their vicinity is analyzed. Similarities
between the different approaches and their peculiarities are highlighted; in
particular, for zero-field bound state in limit of vanishing $\mathscr{E}$, all
three methods produce same results, with their outcomes deviating from each
other according to growing electric intensity.Comment: Accepted for publication in Annalen der Physik (Berlin
First-principle calculations of phononic, electronic and optical
  properties of monolayer arsenene and antimonene allotropes

Recently a stable monolayer of antimony in buckled honeycomb structure called
antimonene was successfully grown on 3D topological insulator Bi$_2$Te$_3$ and
Sb$_2$Te$_3$, which displays semiconducting properties. By first principle
calculations, we systematically investigate the phononic, electronic and
optical properties of $\alpha-$ and $\beta-$ allotropes of monolayer
arsenene/antimonene. We investigate the dynamical stabilities of these four
materials by considering the phonon dispersions. The obtained electronic
structures reveal the direct band gap of monolayer $\alpha-$As/Sb and indirect
band gap of $\beta-$As/Sb. Significant absorption is observed in $\alpha-$Sb,
which can be used as a broad saturable absorber.Comment: 17pages, 9 figure
Regimes of radiative and nonradiative transitions in transport through
  an electronic system in a photon cavity reaching a steady state

We analyze how a multilevel many-electron system in a photon cavity
approaches the steady state when coupled to external leads. When a plunger gate
is used to lower cavity photon dressed one- and two-electron states below the
bias window defined by the external leads, we can identify one regime with
nonradiative transitions dominating the electron transport, and another regime
with radiative transitions. Both transitions trap the electrons in the states
below the bias bringing the system into a steady state. The order of the two
regimes and their relative strength depends on the location of the bias window
in the energy spectrum of the system and the initial conditions.Comment: RevTeX, 6 pages with 7 included eps-figures, references and graphs
  added in resubmissio
Phase transition of charged black holes in massive gravity through new
  methods

Motivated by providing preliminary steps to understand the conception of
quantum gravity, in this paper, we study the phase structure of a semiclassical
gravitational system. We investigate the stability conditions and phase
transition of charged black holes in massive gravity via canonical and
geometrical thermodynamic approaches. We point out the effects of massive
parameter on stability conditions of these black holes and show how massive
coefficients affect the phase transition points of these black holes. We also
study the effects of boundary topology on thermodynamical behavior of the
system. In addition, we give some arguments regarding the role of higher
dimensions and highlight the effect of the electric charge in thermodynamical
behavior. Then, we extend our study to geometrical thermodynamic approach and
show that it can be a successful method for studying the black hole phase
transition. At last, by employing the relation between thermodynamical pressure
and cosmological constant, critical behavior of the system and the effects of
different parameters on critical values are investigated.Comment: 17 pages, 12 figures, change title, published versio
General theory of many body localized systems coupled to baths

We consider what happens when a many body localized system is coupled to a
heat bath. Unlike previous works, we do not restrict ourselves to the limit
where the bath is large and effectively Markovian, nor to the limit where back
action on the bath is negligible. We identify limits where the effect of the
bath can be captured by classical noise, and limits where it cannot. We also
identify limits in which the bath delocalizes the system, as well as limits in
which the system localizes the bath. Using general arguments and dimensional
analysis, we constrain the overall phase diagram of the coupled system and
bath. Our analysis incorporates all the previously discussed regimes, and also
uncovers a new intrinsically quantum regime that has not hitherto been
discussed. We discuss baths that are themselves near a localization transition,
or are strongly disordered but protected against localization by symmetry or
topology. We also discuss situations where the system and bath have different
dimensionality (the case of `boundary MBL' and `boundary baths').Comment: Updated reference
Quantum Zeno Dynamics through stochastic protocols

Quantum Zeno Dynamics is the phenomenon that the observation or strong
driving of a quantum system can freeze its dynamics to a subspace, effectively
truncating the Hilbert space of the system. It represents the quantum version
of the famous flying arrow Zeno paradox. Here, we study how temporal
stochasticity in the system observation (or driving) affects the survival
probability of the system in the subspace. In particular, we introduce a strong
and a weak Zeno regime for which we quantify the confinement by providing an
analytical expression for this survival probability. We investigate several
dissipative and coherent protocols to confine the dynamics, and show that they
can be successfully adapted to the stochastic version. In the weak Zeno regime
the dynamics within the subspace effectively acts as an additional source of
stochasticity in the confinement protocol. Our analytical predictions are
numerically tested and verified on a paradigmatic spin chain. As practical
implications different coherent and dissipative confinement protocols allow to
choose a trade-off between a probabilistic scheme with high fidelity (compared
to perfect subspace dynamics) and a deterministic one with a slightly lower
fidelity, which is a step towards better control in future quantum
technologies.Comment: 9 pages, 5 figure
Theory of invariants-based formulation of ${\bf k}\cdot{\bf p}$
  Hamiltonians with application to strained zinc-blende crystals

Group theoretical methods and ${\bf k}\cdot{\bf p}$ theory are combined to
determine spin-dependent contributions to the effective conduction band
Hamiltonian. To obtain the constants in the effective Hamiltonian, in general
all invariants of the Hamiltonian have to be determined. Hence, we present a
systematic approach to keep track of all possible invariants and apply it to
the ${\bf k}\cdot{\bf p}$ Hamiltonian of crystals with zinc-blende symmetry, in
order to obtain all possible contributions to effective quantities such as
effective mass, g-factor and Dresselhaus constant. Further spin-dependent
contributions to the effective Hamiltonian arise in the presence of strain. In
particular, with regard to the constants $C_3$ and $D$ which describe
spin-splitting linear in the components of ${\bf k}$ and
${\boldsymbol\varepsilon}$, considering all possible terms allowed by symmetry
is crucial.Comment: 17 pages (preprint style
Behaviour of light transmission channels in random media with
  inhomogeneous disorder

We present a numerical study on the light transport properties and statistics
of transmission channels in random media with inhomogeneous disorder. For the
case of longitudinal inhomogeneity of disorder we find that the statistics of
the transmission channels is independent of the inhomogeneity and the system
can be equivalent to a counterpart with homogeneous disorder strength, both of
which have the same statistical distribution of the transmission channels.
However, for the case of transverse inhomogeneity of disorder, such equivalence
does not exist, moreover, the transmission eigenvalues are pushed to the two
ends of the distribution and the distribution of the total transmission is
broadened since the spatial structure gives rise to larger and smaller
transmitted incident channels.Comment: 14 pages, 6 figure
Review of the theoretical description of time-resolved angle-resolved
  photoemission spectroscopy in electron-phonon mediated superconductors

We review recent work on the theory for pump/probe photoemission spectroscopy
of electron-phonon mediated superconductors in both the normal and the
superconducting states. We describe the formal developments that allow one to
solve the Migdal-Eliashberg theory in nonequilibrium for an ultrashort laser
pumping field, and explore the solutions which illustrate the relaxation as
energy is transferred from electrons to phonons. We focus on exact results
emanating from sum rules and approximate numerical results which describe rules
of thumb for relaxation processes. In addition, in the superconducting state,
we describe how Higg's oscillations can be excited due to the nonlinear
coupling with the electric field and how pumping the system can enhance
superconductivity.Comment: 12 pages, 14 figures, submitted to special issue of Annalen der
  Physi
Pseudogap in Eliashberg approach based on electron-phonon and
  electron-electron-phonon interaction

The properties of the superconducting and the anomalous normal state have
been described by using the Eliashberg method. The pairing mechanism has been
reproduced with help of the Hamiltonian, which models the electron-phonon and
electron-electron-phonon interaction (EEPh). The set of the Eliashberg
equations, which determines the order parameter function ($\varphi$), the wave
function renormalization factor ($Z$), and the energy shift function ($\chi$)
has been derived. It has been proven that for the sufficiently large values of
EEPh potential, the doping dependence of order parameter ($\varphi/Z$) has the
analogous course to that observed experimentally in cuprates. The energy gap in
the electron density of states is induced by $Z$ and $\chi$ - the contribution
from $\varphi$ is negligible. The electron density of states possesses the
characteristic asymmetric form and the pseudogap is observed above the critical
temperature.Comment: 12 pages, 8 figure
Connecting the quantum and classical worlds

By considering (non-relativistic) quantum mechanics as it is done in practice
in particular in condensed-matter physics, it is argued that a deterministic,
unitary time evolution within a chosen Hilbert space always has a limited
scope, leaving a lot of room for embedding the quantum-classical transition
into our current theories without recurring to difficult-to-accept
interpretations of quantum mechanics. Nonunitary projections to initial and
final states, the breaking of time-reversal symmetry, a change of Hilbert
space, and the introduction of classical concepts such as external potentials
or localized atomic nuclei are widespread in quantum mechanical calculations.
Furthermore, quantum systems require classical environments that enable the
symmetry breaking that is necessary for creating the atomic configurations of
molecules and crystals. This paper argues that such classical environments are
provided by finite-temperature macroscopic systems in which the range of
quantum correlations and entanglement is limited. This leads to classical
behavior on larger scales, and to collapse-like events in all dynamical
processes that become coupled to the thermalized degrees of freedom.Comment: minor correction
Transport properties in the photonic super-honeycomb lattice - a hybrid
  fermionic and bosonic system

We report on transport properties of the super-honeycomb lattice, the band
structure of which possesses a flat band and Dirac cones, according to the
tight-binding approximation. This super-honeycomb model combines the honeycomb
lattice and the Lieb lattice and displays the properties of both. The
super-honeycomb lattice also represents a hybrid fermionic and bosonic system,
which is rarely seen in nature. By choosing the phases of input beams properly,
the flat-band mode of the super-honeycomb will be excited and the input beams
will exhibit strong localization during propagation. On the other hand, if the
modes of Dirac cones of the super-honeycomb lattice are excited, one will
observe conical diffraction. Furthermore, if the input beam is properly chosen
to excite a sublattice of the super-honeycomb lattice and the modes of Dirac
cones with different pseudospins, e.g., the three-beam interference pattern,
the pseudospin-mediated vortices will be observed.Comment: 13 pages, 7 figures. Comments and criticisms are welcome. Please
  contact Yiqi Zhang directly (zhangyiqi@mail.xjtu.edu.cn
Solitons in one-dimensional lattices with a flat band

We investigate the spectral properties of a quasi-one-dimensional lattice in
two possible dimerisation configurations. Both configurations are characterized
by the same lattice topology and the identical spectra containing a flat band
at zero energy. We find that one of the dimerised configuration has similar
symmetry to a one-dimensional chain proposed by Su-Schrieffer-Heeger for
studying solitons in conjugated polymers. Whereas, the other dimerised
configuration only shows non-trivial topological properties in the presence of
chiral-symmetry breaking adiabatic pumping.Comment: 8 pages, 5 figure
Interacting spinning fermions with quasi-random disorder

Interacting spinning fermions with strong quasi-random disorder are analyzed
via rigorous Renormalization Group (RG) methods combined with KAM techniques.
The correlations are written in terms of an expansion whose convergence follows
from number-theoretical properties of the frequency and cancellations due to
Pauli principle. A striking difference appears between spinless and spinning
fermions; in the first case there are no relevant effective interactions while
in presence of spin an additional relevant quartic term is present in the RG
flow. The large distance exponential decay of the correlations present in the
non interacting case, consequence of the single particle localization, is shown
to persist in the spinning case only for temperatures greater than a power of
the many body interaction, while in the spinless case this happens up to zero
temperature
Quantum Transport in Presence of Bound States -- Noise Power

The impact of bound states in Landauer-Buttiker scattering approach to
non-equilibrium quantum transport is investigated. We show that the noise power
at frequency $\nu$ is sensitive to all bound states with energies $\omega_b$
satisfying $|\omega_b| < \nu$. We derive the exact expression of the bound
state contribution and compare it to the one produced by the scattering states
alone. It turns out that the bound states lead to specific modifications of
both space and frequency dependence of the total noise power. The theoretical
and experimental consequences of this result are discussed.Comment: LaTex 1+11 pages, 4 figure
Review: Local Integrals of Motion in Many-Body Localized systems

We review the current (as of Fall 2016) status of the studies on the emergent
integrability in many-body localized models. We start by explaining how the
phenomenology of fully many-body localized systems can be recovered if one
assumes the existence of a complete set of (quasi)local operators which commute
with the Hamiltonian (local integrals of motion, or LIOMs). We describe the
evolution of this idea from the initial conjecture, to the perturbative
constructions, to the mathematical proof given for a disordered spin chain. We
discuss the proposed numerical algorithms for the construction of LIOMs and the
status of the debate on the existence and nature of such operators in systems
with a many-body mobility edge, and in dimensions larger than one.Comment: Updated version with references added. Review for the special issue
  on "Many-Body Localization" in Annalen der Physik. Comments are welcom
Localization Properties of the XY Spin Chain. A review of mathematical
  results with an eye toward Many-Body Localization

We review several aspects of Many-Body Localization-like properties exhibited
by the disordered XY chains: localization properties of the energy eigenstates
and thermal states, propagation bounds of Lieb-Robinson type, decay of
correlation functions, absence of particle transport, bounds on the bipartite
entanglement, and bounded entanglement growth under the dynamics. We also prove
new results on the absence of energy transport and Fock space localization. All
these properties are made accessible to mathematical analysis due to the exact
mapping of the XY chain to a system of quasi-free fermions given by the
Jordan-Wigner transformation. Motivated by these results we discuss conjectured
properties of more general disordered quantum spin and other systems as
possible directions for future mathematical research.Comment: Final version, to appear in Annalen der Physik; title modified,
  introduction expanded, references added, new Lemma 8.
Extended nonergodic states in disordered many-body quantum systems

This work supports the existence of extended nonergodic states in the
intermediate region between the chaotic (thermal) and the many-body localized
phases. These states are identified through an extensive analysis of static and
dynamical properties of a finite one-dimensional system with onsite random
disorder. The long-time dynamics is particularly sensitive to changes in the
spectrum and in the structures of the eigenstates. The study of the evolution
of the survival probability, Shannon information entropy, and von Neumann
entanglement entropy enables the distinction between the chaotic and the
intermediate region.Comment: 10 pages, 7 figures, Contribution to the Special Issue "Many-Body
  Localization" in Annalen der Physi
Localization-Delocalization Transitions in Bosonic Random Matrix
  Ensembles

Localization to delocalization transitions in eigenfunctions are studied for
finite interacting boson systems by employing one- plus two-body embedded
Gaussian orthogonal ensemble of random matrices [EGOE(1+2)]. In the first
analysis, considered are bosonic EGOE(1+2) for two-species boson systems with a
fictitious ($F$) spin degree of freedom [called BEGOE(1+2)-$F$]. Numerical
calculations are carried out as a function of the two-body interaction strength
($\lambda$). It is shown that, in the region (defined by $\lambda>\lambda_c$)
after the onset of Poisson to GOE transition in energy levels, the strength
functions exhibit Breit-Wigner to Gaussian transition for
$\lambda>\lambda_{F_k}>\lambda_c$. Further, analyzing information entropy and
participation ratio, it is established that there is a region defined by
$\lambda\sim\lambda_t$ where the system exhibits thermalization. The $F$-spin
dependence of the transition markers $\lambda_{F_k}$ and $\lambda_t$ follow
from the propagator for the spectral variances. These results, well tested near
the center of the spectrum and extend to the region within $\pm2\sigma$ to
$\pm3\sigma$ from the center ($\sigma^2$ is the spectral variance), establish
universality of the transitions generated by embedded ensembles. In the second
analysis, entanglement entropy is studied for spin-less BEGOE(1+2) ensemble and
shown that the results generated are close to the recently reported results for
a Bose-Hubbard model.Comment: 11 pages, 6 figures, Contribution to the Special Issue "Many-Body
  Localization" in Annalen der Physi
Localization and chaos in a spin glass model with random fields: Mapping
  to the localization problem in a Bethe lattice with a correlated disorder

The analytical solution of a many-body localization problem in a quantum
Sherrington-Kirkpatrick spin glass model in a random longitudinal field is
proposed matching the problem with a model of Anderson localization in a Bethe
lattice. The localization transition is dramatically sensitive to the
relationship between interspin interaction and random field revealing different
regimes in which the interaction can either suppress or enhance the
delocalization. The localization is enhanced by decreasing the temperature and
the localization transition shows a remarkable universality in a spin glass
phase. The observed trends should be qualitatively relevant for other systems
showing many-body localization.Comment: 15 pages, 5 figures, Revised version, accepted by Annalen der Physik
  for publication in the Special Issue dedicated to Many Body Localizatio
Density-Matrix Renormalization Group study of Many-Body Localization in
  Floquet Eigenstates

We generalize the recently introduced Density-Matrix Renormalization Group
(DMRG-X) [Khemani et al, PRL 2016] algorithm to obtain Floquet eigenstates of
one-dimensional, periodically driven many-body localized systems. This
generalization is made possible by the fact that the time-evolution operator
for a period can be efficiently represented using a matrix-product operator. We
first benchmark the method by comparing to exact diagonalization for small
systems. We then obtain Floquet eigenstates for larger systems and show
unambiguously that the characteristic area-law scaling remains robust.Comment: 7 pages, 4 figure
Dephasing enhanced spin transport in the ergodic phase of a many-body
  localizable system

We study high temperature spin transport in a disordered Heisenberg chain in
the ergodic regime when bulk dephasing is present. We find that while dephasing
always renders the transport diffusive, there is nonetheless a remnant of the
diffusive to sub-diffusive transition found in a system without dephasing
manifested in the behaviour of the diffusion constant with the dephasing
strength. By studying finite-size effects we show numerically and theoretically
that this feature is caused by the competition between large crossover length
scales associated to disorder and dephasing that control the dynamics observed
in the thermodynamic limit. We demonstrate that this competition may lead to a
dephasing enhanced transport in this model.Comment: Included schematic diagram of the dependence of diffusion constant on
  dephasing strength and disorder strength (figure 10