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QUROPE - aggregated feeds in category PhysicsenarXiv.org: Quantum Physics: Superdiffusion in spin chains. (arXiv:2103.01976v1 [cond-mat.stat-mech])
http://arxiv.org/abs/2103.01976
<p>This review summarizes recent advances in our understanding of anomalous
transport in spin chains, viewed through the lens of integrability. Numerical
advances, based on tensor-network methods, have shown that transport in many
canonical integrable spin chains -- most famously the Heisenberg model -- is
anomalous. Concurrently, the framework of generalized hydrodynamics has been
extended to explain some of the mechanisms underlying anomalous transport.<p><a href="http://arxiv.org/abs/2103.01976">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Open Quantum-System Simulation of Faraday's Induction Law via Dynamical Instabilities. (arXiv:2103.01979v1 [cond-mat.quant-gas])
http://arxiv.org/abs/2103.01979
<p>We propose a novel type of a Bose-Hubbard ladder model based on an open
quantum-gas--cavity-QED setup to study the physics of dynamical gauge
potentials. Atomic tunneling along opposite directions in the two legs of the
ladder is mediated by photon scattering from transverse pump lasers to two
distinct cavity modes. The resulting interplay between cavity photon
dissipation and the optomechanical atomic back-action then induces an
average-density-dependent dynamical gauge field.<p><a href="http://arxiv.org/abs/2103.01979">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Polaritonic states of matter in rotating cavity. (arXiv:2103.01984v1 [quant-ph])
http://arxiv.org/abs/2103.01984
<p>The interaction of quantum light with matter like that inside a cavity is
known to give rise to mixed light-matter states called polaritons. We discuss
the impact of rotation of the cavity on the polaritons. It is shown that the
number of polaritons increases due to this rotation. The structure of the
original polaritons is modified and new ones are induced by the rotation that
strongly depend on the angular velocity and the choice of axis of rotation.<p><a href="http://arxiv.org/abs/2103.01984">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Thermal entanglement in $2\otimes3$ Heisenberg chains via distance between states. (arXiv:2103.02019v1 [quant-ph])
http://arxiv.org/abs/2103.02019
<p>Most of the work involving entanglement measurement focuses on systems that
can be modeled by two interacting qubits. This is due to the fact that there
are few studies presenting entanglement analytical calculations in systems with
spins $s > 1/2$. In this paper we present for the first time an analytical way
of calculating thermal entanglement in a dimension $2\otimes3$ Heisenberg chain
through the distance between states. We use the Hilbert-Schmidt norm to obtain
entanglement.<p><a href="http://arxiv.org/abs/2103.02019">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Approximations based on density-matrix embedding theory for density-functional theories. (arXiv:2103.02027v1 [physics.chem-ph])
http://arxiv.org/abs/2103.02027
<p>Recently a novel approach to find approximate exchange-correlation
functionals in density-functional theory (DFT) was presented (U. Mordovina et.
al., JCTC 15, 5209 (2019)), which relies on approximations to the interacting
wave function using density-matrix embedding theory (DMET). This approximate
interacting wave function is constructed by using a projection determined by an
iterative procedure that makes parts of the reduced density matrix of an
auxiliary system the same as the approximate interacting density matrix.<p><a href="http://arxiv.org/abs/2103.02027">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Completely synchronizing quantum channels. (arXiv:2103.02031v1 [quant-ph])
http://arxiv.org/abs/2103.02031
<p>We investigate the most general mechanisms that lead to perfect
synchronization of the quantum states of all subsystems of an open quantum
system starting from an arbitrary initial state. We provide a necessary and
sufficient condition for such "quantum-state synchronization", prove tight
lower bounds on the dimension of the environment's Hilbert space in two main
classes of quantum-state synchronizers, and give an analytical solution for
their construction.<p><a href="http://arxiv.org/abs/2103.02031">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Implementation of Quantum Machine Learning for Electronic Structure Calculations of Periodic Systems on Quantum Computing Devices. (arXiv:2103.02037v1 [physics.comp-ph])
http://arxiv.org/abs/2103.02037
<p>Quantum machine learning algorithms, the extensions of machine learning to
quantum regimes, are believed to be more powerful as they leverage the power of
quantum properties. Quantum machine learning methods have been employed to
solve quantum many-body systems and have demonstrated accurate electronic
structure calculations of lattice models, molecular systems, and recently
periodic systems.<p><a href="http://arxiv.org/abs/2103.02037">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Coherent control and distinguishability of quantum channels via PBS-diagrams. (arXiv:2103.02073v1 [quant-ph])
http://arxiv.org/abs/2103.02073
<p>We introduce a graphical language for coherent control of general quantum
channels inspired by practical quantum optical setups involving polarising beam
splitters (PBS). As standard completely positive trace preserving maps are
known not to be appropriate to represent coherently controlled quantum
channels, we propose to instead use purified channels, an extension of
Stinespring's dilation. We characterise the observational equivalence of
purified channels in various coherent-control contexts, paving the way towards
a faithful representation of quantum channels under coherent control.
</p>Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Computing Sum of Sources over a Classical-Quantum MAC. (arXiv:2103.02082v1 [cs.IT])
http://arxiv.org/abs/2103.02082
<p>We consider the problem of communicating a general bivariate function of two
classical sources observed at the encoders of a classical-quantum multiple
access channel. Building on the techniques developed for the case of a
classical channel, we propose and analyze a coding scheme based on coset codes.
The proposed technique enables the decoder recover the desired function without
recovering the sources themselves. We derive a new set of sufficient conditions
that are weaker than the current known for identified examples.<p><a href="http://arxiv.org/abs/2103.02082">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100arXiv.org: Quantum Physics: Dissipative preparation of W states in trapped ion systems. (arXiv:2103.02088v1 [quant-ph])
http://arxiv.org/abs/2103.02088
<p>We present protocols for dissipative entanglement of three trapped-ion qubits
and discuss a scheme that uses sympathetic cooling as the dissipation
mechanism. This scheme relies on tailored destructive interference to generate
any one of six entangled W states in a three-ion qubit space. Using a
beryllium-magnesium ion crystal as an example system, we theoretically
investigate the protocol's performance and the effects of likely error sources,
including thermal secular motion of the ion crystal, calibration imperfections,
and spontaneous photon scattering.<p><a href="http://arxiv.org/abs/2103.02088">read more</a></p>
Thu, 04 Mar 2021 11:25:50 +0100