pinecone/core-2020-05-10-deduplication huggingface dataset:
Thermalization of isolated Bose-Einstein condensates by dynamical heat
  bath generation

If and how an isolated quantum system thermalizes despite its unitary time
evolution is a long-standing, open problem of many-body physics. The eigenstate
thermalization hypothesis (ETH) postulates that thermalization happens at the
level of individual eigenstates of a system's Hamiltonian. However, the ETH
requires stringent conditions to be validated, and it does not address how the
thermal state is reached dynamically from an inital non-equilibrium state. We
consider a Bose-Einstein condensate (BEC) trapped in a double-well potential
with an initial population imbalance. We find that the system thermalizes
although the initial conditions violate the ETH requirements. We identify three
dynamical regimes. After an initial regime of undamped Josephson oscillations,
the subsystem of incoherent excitations or quasiparticles (QP) becomes strongly
coupled to the BEC subsystem by means of a dynamically generated, parametric
resonance. When the energy stored in the QP system reaches its maximum, the
number of QPs becomes effectively constant, and the system enters a
quasi-hydrodynamic regime where the two subsystems are weakly coupled. In this
final regime the BEC acts as a grand-canonical heat reservoir for the QP system
(and vice versa), resulting in thermalization. We term this mechanism dynamical
bath generation (DBG).Comment: Published version, 20 pages, 19 figures, minor grammar and typos
  correcte
Unveiling the link between fractional Schr\"odinger equation and light
  propagation in honeycomb lattice

We establish a link between the fractional Schr\"odinger equation (FSE) and
light propagation in the honeycomb lattice (HCL) - the Dirac-Weyl equation
(DWE). The fractional Laplacian in FSE causes a modulation of the dispersion
relation of the system, which in the limiting case becomes linear. In the HCL,
the dispersion relation is already linear around the Dirac point, suggesting a
possible connection with the FSE. Here, we demonstrate this connection by
describing light propagation in both FSE and HCL, using DWE. Thus, we propagate
Gaussian beams according to FSE, HCL around the Dirac point, and DWE, to
discover very similar behavior - the conical diffraction. However, if an
additional potential is brought into the system, the link between FSE and HCL
is broken, because the added potential serves as a perturbation, which breaks
the translational periodicity of HCL and destroys Dirac cones in the dispersion
relation.Comment: 6 pages, 4 figures. Comments and criticisms are welcome (Yiqi Zhang:
  zhangyiqi@mail.xjtu.edu.cn
Lower order and higher order entanglement in $87Rb$ $5S-5P-5D$ hyperfine
  manifold modeled as a four-wave mixing process

Possibilities of generation of lower order and higher order intermodal
entanglement in 87Rb 5S-5P-5D hyperfine manifold are rigorously investigated
using Sen-Mandal perturbative technique by showing the equivalence of the
system with the four-wave mixing (FWM) process. The investigation has revealed
that for a set of experimentally realizable/relevant parameters we can observe
lower order and higher order intermodal entanglement between pump and signal
modes, signal and idler modes, and idler and pump modes in a FWM process
associated with the 87Rb 5S-5P-5D hyperfine manifold. In addition, trimodal
entanglement involving pump, signal and idler modes is also reported.Comment: 12 pages, 5 figure
Spatial Filters on Demand Based on Aperiodic Photonic Crystals

Photonic Crystal spatial filters, apart from stand-alone spatial filtering function, can also suppress multi-transverse-mode operation in laser resonators. Here it is shown that such photonic crystals can be designed by solving the inverse problem: for a given spatial filtering profile. Optimized Photonic Crystal filters were fabricated in photosensitive glass. Experiments have shown that such filters provide a more pronounced filtering effect for total and partial transmissivity conditions.Peer ReviewedPostprint (published version
Recent progress in many-body localization

This article is a brief introduction to the rapidly evolving field of
many-body localization. Rather than giving an in-depth review of the subject,
our aspiration here is simply to introduce the problem and its general context,
outlining a few directions where notable progress has been achieved in recent
years. We hope that this will prepare the readers for the more specialized
articles appearing in the forthcoming dedicated volume of Annalen der Physik,
where these developments are discussed in more detail.Comment: Invited overview article for the Special Volume of Annalen der Physik
  on Many-Body Localizatio
Is Teleparallel Gravity really equivalent to General Relativity?

An axiomatization of the so-called Teleparallel Equivalent to General
Relativity is presented. A set of formal and semantic postulates are elaborated
from where the physical meaning of various key concepts of the theory are
clarified. These concepts include those of inertia, Lorentz and diffeomorphism
invariance, and reference frame. It is shown that Teleparallel Gravity admits a
wider representation of space-time than General Relativity, allowing to define
properties of the gravitational field such as energy and momentum that are
usually considered problematic. In this sense, although the dynamical equations
of both theories are equivalent, their inequivalence from a physical point of
view is demonstrated. Finally, the axiomatic formulation is used to compare
Teleparallel Gravity with other theories of gravity based on absolute
parallelism such as non-local and f(T) gravity.Comment: 21 pages, accepted for publication in Annalen der Physi
Thermodynamic parameters of single- or multi-band superconductors
  derived from self-field critical currents

Key questions for any superconductor include: what is its maximum
dissipation-free electrical current (its `critical current') and can this be
used to extract fundamental thermodynamic parameters? Present models focus on
depinning of magnetic vortices and implicate materials engineering to maximise
pinning performance. But recently we showed that the self-field critical
current for thin films is a universal property, independent of microstructure,
controlled only by the penetration depth. Here we generalise this observation
to include thin films, wires or nanowires of single- or multi-band s-wave and
d-wave superconductors. Using extended BCS theory we consider dissipation-free
self-field transport currents as Meissner-London currents, avoiding the concept
of pinning altogether. We find quite generally, for type I or type II
superconductors, the current is limited by the relevant critical field divided
by the penetration depth. Our fits to 62 available data sets, from zinc
nanowires to compressed sulphur hydride with critical temperatures of 0.65 to
203 K, respectively, are excellent. Extracted London penetration depths,
superconducting energy gaps and specific heat jumps agree well with reported
bulk values. For multiband or multiphase samples we accurately recover
individual band contributions and phase fractions.Comment: 14 pages, 6 figures, 5 tables submitted to Phys. Rev.
Holographical aspects of dyonic black holes: Massive gravity
  generalization

The content of this paper includes studying holographical and thermodynamical
aspects of dyonic black holes in the presence of massive gravity. For the first
part of paper, thermodynamical properties of the bulk which includes black
holes are studied and the main focus is on critical behavior. It will be shown
that the existence of massive gravitons introduces remnant for temperature
after evaporation of black holes, van der Waals phase transition for
non-spherical black holes and etc. The consistency of different thermodynamical
approaches toward critical behavior of the black holes is presented and the
physical properties near the region of thermal instability are given. Next part
of the paper studies holographical aspects of the boundary theory.
Magnetization and susceptibility of the boundary are extracted and the
conditions for having diamagnetic and paramagnetic behaviors are investigated.
It will be shown that generalization to massive gravity results into the
existence of diamagnetic/paramagnetic phases in phase structure of the
hyperbolic and horizon flat of boundary conformal field theory.Comment: 29 pages, 18 figures. Accepted for publication in Ann. Phys. (Berlin
Intertial Frame Dragging in an Acoustic Analogue spacetime

We report an incipient exploration of the Lense-Thirring precession effect in
a rotating \textit{acoustic analogue black hole} spacetime. An exact formula is
deduced for the precession frequency of a gyroscope due to inertial frame
dragging, close to the ergosphere of a `Draining Bathtub' acoustic spacetime
which has been studied extensively for acoustic Hawking radiation of phonons
and also for `superresonance'. The formula is verified by embedding the two
dimensional spatial (acoustic) geometry into a three dimensional one where the
similarity with standard Lense-Thirring precession results within a strong
gravity framework is well known. Prospects of experimental detection of this
new `fixed-metric' effect in acoustic geometries, are briefly discussed.Comment: LaTex; 6 pages including 1 figure; paper thoroughly revised, accepted
  for publication in Annalen der Physi
Spin-1 Bose Hubbard model with nearest neighbour extended interaction

We have studied a spinor (F = 1) Bose gas in presence of the density-density
interaction through the mean field approach and the perturbation theory for
either sign of the spin dependent interaction, namely the antiferromagnetic
(AF) and the ferromagnetic cases. In the AF case, the charge density wave (CDW)
phase appears to be sandwiched between the Mott insulating (MI) and the
supersolid phases for small values of the extended interaction strength. But
the CDW phase completely occupies the MI lobe when the extended interaction
strength is larger than a certain critical value related to the width of the MI
lobes and hence opens up the possibilities of spin singlet and nematic CDW
insulating phases. In the ferromagnetic case, the phase diagram shows similar
features as that of the AF case and are in complete agreement with a spin-0
Bose gas. The perturbation expansion calculations nicely corroborate the mean
field phase results in both these cases. Further, we extend our calculations in
presence of a harmonic confinement and obtained the momentum distribution
profile that is related to the absorption spectra in order to distinguish
between different phases
Improving shortcuts to non-Hermitian adiabaticity for fast population
  transfer in open quantum systems

It is still a challenge to experimentally realize shortcuts to adiabaticity
(STA) for a non-Hermitian quantum system since a non-Hermitian quantum system's
counterdiabatic driving Hamiltonian contains some unrealizable auxiliary
control fields. In this paper, we relax the strict condition in constructing
STA and propose a method to redesign a realizable supplementary Hamiltonian to
construct non-Hermitian STA. The redesigned supplementary Hamiltonian can be
eithersymmetric or asymmetric. For the sake of clearness, we apply this method
to an Allen-Eberly model as an example to verify the validity of the optimized
non-Hermitian STA. The numerical simulation demonstrates that a ultrafast
population inversion could be realized in a two-level non-Hermitian system.Comment: 11 pages, 4 figures, has been accepted by Annalen Der Physi
Monogamy of Einstein-Podolsky-Rosen steering in the background of an
  asymptotically flat black hole

We study the behavior of monogamy deficit and monogamy asymmetry for
Einstein-Podolsky-Rosen steering of Gaussian states under the influence of the
Hawking effect. We demonstrate that the monogamy of quantum steering shows an
extreme scenario in the curved spacetime: the first part of a tripartite system
cannot individually steer two other parties, but it can steer the collectivity
of the remaining two parties. We also find that the monogamy deficit of
Gaussian steering, a quantifier of genuine tripartite steering, are generated
due to the influence of the Hawking thermal bath. Our results elucidate the
structure of quantum steering in tripartite quantum systems in curved
spacetime.Comment: 16 pages, 4 figure
Spin Hall magnetoresistance and spin Nernst magnetothermopower: role of
  the inverse spin galvanic effect

In ferromagnet/normal-metal bilayers, the sensitivity of the spin Hall
magnetoresistance and the spin Nernst magnetothermopower to the boundary
conditions at the interface is of central importance. In general, such boundary
conditions can be substantially affected by current-induced spin polarizations.
In order to quantify the role of the latter, we consider a Rashba
two-dimensional electron gas with a ferromagnet attached to one side of the
system. The geometry of such a system maximizes the effect of current-induced
spin polarization on the boundary conditions, and the spin Hall
magnetoresistance is shown to acquire a non-trivial and asymmetric dependence
on the magnetization direction of the ferromagnet.Comment: 20 pages, 7 figure
Pair Events in Superluminal Optics

When an object moves faster than emissions it creates, it may appear at two
positions simultaneously. The appearance or disappearance of this bifurcation
is referred to as a pair event. Inherently convolved with superluminal motion,
pair events have no subluminal counterparts. Common examples of superluminal
motions that exhibit pair events include Cherenkov radiation, sonic booms,
illumination fronts from variable light sources, and rotating beams. The
minimally simple case of pair events from a single massive object is explored
here: uniform linear motion. A pair event is perceived when the radial
component of the object's speed toward the observer drops from superluminal to
subluminal. Emission from the pair creation event will reach the observer
before emission from either of the two images created. Potentially observable
image pair events are described for sonic booms and Cherenkov light. To date,
no detection of discrete images following a projectile pair event have ever
been reported, and so the pair event nature of sonic booms and Cherenkov
radiation, for example, remains unconfirmed. Recent advances in modern
technology have made such pair event tracking feasible. If measured, pair
events could provide important information about object distance and history.Comment: 13 pages, 3 figures. in press: Annalen der Physi
Electroluminescence caused by the transport of interacting electrons
  through parallel quantum dots in a photon cavity

We show that a Rabi-splitting of the states of strongly interacting electrons
in parallel quantum dots embedded in a short quantum wire placed in a photon
cavity can be produced by either the para- or the dia-magnetic electron-photon
interactions when the geometry of the system is properly accounted for and the
photon field is tuned close to a resonance with the electron system. We use
these two resonances to explore the electroluminescence caused by the transport
of electrons through the one- and two-electron ground states of the system and
their corresponding conventional and vacuum electroluminescense as the central
system is opened up by coupling it to external leads acting as electron
reservoirs. Our analysis indicates that high-order electron-photon processes
are necessary to adequately construct the cavity-photon dressed electron states
needed to describe both types of electroluminescence.Comment: RevTeX, 14 pages with 18 eps-figures include
Effective equations for repulsive quasi-1D BECs trapped with anharmonic
  transverse potentials

One-dimensional nonlinear Schr\"odinger equations are derived to describe the
axial effective dynamics of cigar-shaped atomic repulsive Bose-Einstein
condensates trapped with anharmonic transverse potentials. The accuracy of
these equations in the perturbative, Thomas-Fermi, and crossover regimes were
verified numerically by comparing the ground-state profiles, transverse
chemical potentials and oscillation patterns with those results obtained for
the full three-dimensional Gross-Pitaevskii equation. This procedure allows us
to derive different patterns of 1D nonlinear models by the control of the
transverse confinement.Comment: 6 pages, 5 figure
Lattices and Their Consistent Quantification

This paper introduces the order-theoretic concept of lattices along with the
concept of consistent quantification where lattice elements are mapped to real
numbers in such a way that preserves some aspect of the order-theoretic
structure. Symmetries, such as associativity, constrain consistent
quantification and lead to a constraint equation known as the sum rule.
Distributivity in distributive lattices also constrains consistent
quantification and leads to a product rule. The sum and product rules, which
are familiar from, but not unique to, probability theory, arise from the fact
that logical statements form a distributive (Boolean) lattice, which exhibits
the requisite symmetries.Comment: 33 pages, 8 figure
Relativistic Heat Equation via L\'{e}vy stable distributions: Exact
  Solutions

We introduce and study an extension of the heat equation relevant to
relativistic energy formula involving square root of differential operators. We
furnish exact solutions of corresponding Cauchy (initial) problem using the
operator formalism invoking one-sided L\'{e}vy stable distributions. We note a
natural appearance of Bessel polynomials which allow one the obtention of
closed form solutions for a number of initial conditions. The resulting
relativistic diffusion is slower than the non-relativistic one, although it
still can be termed a normal one. Its detailed statistical characterization is
presented in terms of exact evaluation of arbitrary moments and is compared
with the non-relativistic case
Quantum Measurements, Energy Conservation and Quantum Clocks

We consider a spin chain extending from Alice to Bob with next neighbors
interactions, initially in its ground state. Assuming that Bob measures the
last spin of the chain, the energy of the spin chain has to increase, at least
on average, due to the measurement disturbance. Presumably, the energy is
provided by Bob's measurement apparatus. Assuming now that, simultaneously to
Bob's measurement, Alice measures the first spin, we show that either energy is
not conserved, - implausible - or the projection postulate doesn't apply, and
that there is signalling. An explicit measurement model shows that energy is
conserved (as expected), but that the spin chain energy increase is not
provided by the measurement apparatus(es), that the projection postulate is not
always valid - illustrating the Wigner-Araki-Yanase (WAY) theorem - and that
there is signalling, indeed. The signalling is due to the non-local interaction
Hamiltonian. This raises the question of a suitable quantum information
inspired model of such non-local Hamiltonians.Comment: 7 pages + appendices, 6 figure
Universal distributed quantum computing on superconducting qutrits with
  dark photons

We present a one-step scheme to construct the controlled-phase gate
deterministically on remote transmon qutrits coupled to different resonators
connected by a superconducting transmission line for an universal distributed
quantum computing. Different from previous works on remote superconducting
qubits, the present gate is implemented with coherent evolutions of the entire
system in the all-resonance regime assisted by the dark photons to robust
against the transmission line loss, which allows the possibility of the complex
designation of a long-length transmission line to link lots of circuit QEDs.
The length of the transmission line can reach the scale of several meters,
which makes our scheme is suitable for the large-scale distributed quantum
computing. This gate is a fast quantum entangling operation with a high
fidelity of about 99%. Compare with previous works in other quantum systems for
a distributed quantum computing, under the all-resonance regime, the present
proposal does not require classical pulses and ancillary qubits, which relaxes
the difficulty of its implementation largely.Comment: 10 pages, 4 figures, one colum
Lorentz Violation and Topologically Trapped Charge Carriers in 2D
  Materials

The full spectrum of two-dimensional fermion states in a scalar soliton trap
with a Lorentz breaking background is investigated in the context of the novel
2D materials, where the Lorentz symmetry should not be strictly valid. The
field theoretical model with Lorentz breaking terms represents Dirac electrons
in one valley and in a scalar field background. The Lorentz violation comes
from the difference between the Dirac electron and scalar mode velocities,
which should be expected when modelling the electronic and lattice excitations
in 2D materials. We extend the analytical methods developed in the context of
1+1 field theories to explore the effect of the Lorentz symmetry breaking in
the charge carrier density of 2D materials in the presence of a domain wall
with a kink profile. The width and the depth of the trapping potential from the
kink is controlled by the Lorentz violating term, which is reflected
analytically in the band structure and properties of the trapped states. Our
findings enlarge previous studies of the edge states obtained with domain wall
and in strained graphene nanoribbon in a chiral gauge theory
Geometric Potential Resulting from Dirac Quantization

A fundamental problem regarding the Dirac quantization of a free particle on
an $N-1$ curved hypersurface embedded in $N$($\geq 2$) flat space is the
impossibility to give the same form of the curvature-induced quantum potential,
the geometric potential as commonly called, as that given by the
Schr\"{o}dinger equation method where the particle moves in a region confined
by a thin-layer sandwiching the surface. We resolve this problem by means of
previously proposed scheme that hypothesizes a simultaneous quantization of
positions, momenta, and Hamiltonian, among which the operator-ordering-free
section is identified and is then found sufficient to lead to the expected form
of geometric potential.Comment: 5 pages, 0 figure. corrected typos. arXiv admin note: text overlap
  with arXiv:1701.0837
Optical switch based on dressed intracavity dark states

We present a scheme to realize two-direction optical switch by a single-mode
optical cavity containing some four-level atoms. The high switching efficiency
can be obtained through low photon loss and large third-order nonlinear
susceptibility of this N-type atomic system in cavity. Without the microwave
source, it can be reduced to an atomic system where a coupling laser is used to
realize single electromagnetically induced transparency. Namely, the probe
field can be transmitted almost totally at resonance. Thus a two-direction
optical switch is operated and the state for forward (backward) direction is
set as open (closed). When microwave source is introduced, dressed splitting of
dark state happens. The probe field is reflected almost completely at resonance
and the state of the optical switch at forward and backward directions
(transmitted and reflected channels) is shifted as closed and open,
respectively. Moreover, this scheme is much advantageous to realize splitting
of dark state because weak microwave field induces the coupling between dark
state and one sub-level of ground state. While a strong pump laser which
couples dark state with an excited level is applied to realize this splitting
in Ref. [Phys. Rev. A 85 013814 (2012)].Comment: 7 pages, 7 figure