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We derive a semi-classical nonequilibrium work identity by applying the Wigner-Weyl quantization scheme to the Jarzynski identity for a classical Hamiltonian. This allows us, to the leading order in $\hbar$, to overcome the problem of…

Quantum Physics · Physics 2020-09-25 O. Brodier , K. Mallick , A. M. Ozorio de Almeida

The formalism of classical and quantum mechanics on phase space leads to symplectic and Heisenberg group representations, respectively. The Wigner functions give a representation of the quantum system using classical variables. The…

Quantum Physics · Physics 2007-05-23 Ajay Patwardhan

In this paper a notion of entropy transmission of quantum channels is introduced as a natural extension of Ohya's entropy. Here by quantum channel is meant unital completely positive mappings (ucp) of $B(H)$ into itself, where $H$ is an…

Quantum Physics · Physics 2007-11-21 Nasir Ganikhodjaev , Farrukh Mukhamedov

We study different notions of quantum correlations in multipartite systems of distinguishable and indistinguishable particles. Based on the definition of quantum coherence for a single particle, we consider two possible extensions of this…

Quantum Physics · Physics 2017-09-27 Jan Sperling , Armando Perez-Leija , Kurt Busch , Ian A. Walmsley

Coherent superposition is a key feature of quantum mechanics that underlies the advantage of quantum technologies over their classical counterparts. Recently, coherence has been recast as a resource theory in an attempt to identify and…

Coherence arises from the superposition principle and plays a key role in quantum mechanics. Recently, Baumgratz et al. [T. Baumgratz, M. Cramer, and M. B. Plenio, Phys. Rev. Lett. 113, 140401 (2014)] established a rigorous framework for…

Quantum Physics · Physics 2016-03-23 Jianwei Xu

We provide lower and upper bounds on the information transmission capacity of one single use of a classical-quantum channel. The lower bound is expressed in terms of the Hoeffding capacity, that we define similarly to the Holevo capacity,…

Quantum Physics · Physics 2009-07-24 Milan Mosonyi , Nilanjana Datta

We construct physical semi-classical states annihilated by the Hamiltonian constraint operator in the framework of loop quantum cosmology as a method of systematically determining the regime and validity of the semi-classical limit of the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Parampreet Singh , Kevin Vandersloot

The striking differences between quantum and classical systems predicate disruptive quantum technologies. We peruse quantumness from a variety of viewpoints, concentrating on phase-space formulations because they can be applied beyond…

Quantum Physics · Physics 2020-12-07 Aaron Z. Goldberg , Andrei B. Klimov , Markus Grassl , Gerd Leuchs , Luis L. Sánchez-Soto

Quantitative analysis of discontinuity of basic characteristics of quantum states and channels is presented. First we consider general estimates for discontinuity jump (loss) of the von Neumann entropy for a given converging sequence of…

Quantum Physics · Physics 2021-09-28 M. E. Shirokov

When a quantum state undergoes a quantum channel, the state will be inevitably influenced. In general, the fidelity of the state is reduced, so is the entanglement if the sub- systems go through the channel. However, the influence on the…

Quantum Physics · Physics 2014-11-04 Lin Wang , Chang-shui Yu

Effective information transmission is a central element in quantum information protocols, but the quest for optimal efficiency in channels with symmetrical characteristics remains a prominent challenge in quantum information science. In…

Quantum Physics · Physics 2023-11-02 Atta ur Rahman , S. M. Zangi , Ma-Cheng Yang , Cong-Feng Qiao

Entanglement is a purely quantum mechanical phenomenon and thus it has no classical analog. On the other hand, coherence is a well-known phenomenon in classical optics and in quantum mechanics. Recent research shows that quantum coherence…

Quantum Physics · Physics 2023-02-14 Anu Kumari , Satyabrata Adhikari

It was at the dawn of the historical developments of quantum mechanics when Schr\"odinger, Kennard and Darwin proposed an interesting type of Gaussian wave packets, which do not spread out while evolving in time. Originally, these wave…

Quantum Physics · Physics 2018-08-09 Sanjib Dey , Andreas Fring , Véronique Hussin

We present a theory of coherent quantum transport in ferromagnetic/ non-magnetic/ ferromagnetic heterojunctions. We predict quantum coherence to give rise to a quantum spin valve effect that, unlike its familiar classical analog, occurs…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Francisco Mireles , George Kirczenow

The emerging quantum technologies rely on our ability to establish and control quantum systems in nonclassical states, exhibiting entanglement and quantum coherence. It is thus crucial to understand how entanglement and coherence can be…

Quantum Physics · Physics 2022-06-22 Masaya Takahashi , Swapan Rana , Alexander Streltsov

The study of quantum quenches in integrable systems has significantly advanced with the introduction of the Quench Action method, a versatile analytical approach to non-equilibrium dynamics. However, its application is limited to those…

Statistical Mechanics · Physics 2016-08-24 Lorenzo Piroli , Eric Vernier , Pasquale Calabrese

We discuss conditional Renyi and Tsallis entropies for bipartite quantum systems of finite dimension. We investigate the relation between the positivity of conditional entropies and entanglement properties. It is in particular shown that…

Quantum Physics · Physics 2009-11-07 Karl Gerd H. Vollbrecht , Michael M. Wolf

We consider the description of open quantum systems with probability sinks (or sources) in terms of general non-Hermitian Hamiltonians.~Within such a framework, we study novel possible definitions of the quantum linear entropy as an…

Quantum Physics · Physics 2016-12-20 Alessandro Sergi , Paolo V. Giaquinta

Quantum embedding theories are promising approaches to investigate strongly-correlated electronic states of active regions of large-scale molecular or condensed systems. Notable examples are spin defects in semiconductors and insulators. We…

Materials Science · Physics 2021-12-14 He Ma , Nan Sheng , Marco Govoni , Giulia Galli
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