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We show that Frenkel's integral representation of the quantum relative entropy provides a natural framework to derive continuity bounds for quantum information measures. Our main general result is a dimension-independent semi-continuity…

Quantum Physics · Physics 2025-03-04 Mario Berta , Ludovico Lami , Marco Tomamichel

The Wehrl entropy is an entropy associated to the Husimi quasi-probability distribution. We discuss how it can be used to formulate entropic uncertainty relations and for a quantification of entanglement in continuous variables. We show…

Quantum Physics · Physics 2021-06-29 Stefan Floerchinger , Tobias Haas , Henrik Müller-Groeling

We study the decoherence of a renormalised quantum field theoretical system. We consider our novel correlator approach to decoherence where entropy is generated by neglecting observationally inaccessible correlators. Using…

High Energy Physics - Theory · Physics 2011-04-22 Jurjen F. Koksma , Tomislav Prokopec , Michael G. Schmidt

We study nonclassical correlations beyond entanglement in a family of two-mode non-Gaussian states which represent the continuous-variable counterpart of two-qubit Werner states. We evaluate quantum discord and other quantumness measures…

Quantum Physics · Physics 2015-06-03 Richard Tatham , Ladislav Mišta , Gerardo Adesso , Natalia Korolkova

A model of quantum noisy channel with input encoding by a classical random vector is described. An equation of optimality is derived to determine a complete set of wave functions describing quantum decodings based on quasi-measurements…

Quantum Physics · Physics 2007-05-23 V. P. Belavkin , R. L. Stratonovich

The minimum Renyi and Wehrl output entropies are found for bosonic channels in which the signal photons are either randomly displaced by a Gaussian distribution (classical-noise channel), or in which they are coupled to a thermal…

Quantum Physics · Physics 2009-11-10 Vittorio Giovannetti , Seth Lloyd , Lorenzo Maccone , Jeffrey H. Shapiro , Brent J. Yen

Quantum communication is an important branch of quantum information science, promising unconditional security to classical communication and providing the building block of a future large-scale quantum network. Noise in realistic quantum…

Quantum Physics · Physics 2020-01-24 Kyungjoo Noh , Stefano Pirandola , Liang Jiang

In this Letter we exploit the recently-solved conjecture on the bosonic minimum output entropy to show the optimality of Gaussian discord, so that the computation of quantum discord for bipartite Gaussian states can be restricted to local…

Quantum amplifier channels are at the core of several physical processes. Not only do they model the optical process of spontaneous parametric down-conversion, but the transformation corresponding to an amplifier channel also describes the…

Quantum Physics · Physics 2017-02-02 Haoyu Qi , Mark M. Wilde

It is shown that the capacity of a classical-quantum channel with arbitrary (possibly mixed) states equals to the maximum of the entropy bound with respect to all apriori distributions. This completes the recent result of Hausladen, Jozsa,…

Quantum Physics · Physics 2007-05-23 A. S. Holevo

Estimating quantum entropies and divergences is an important problem in quantum physics, information theory, and machine learning. Quantum neural estimators (QNEs), which utilize a hybrid classical-quantum architecture, have recently…

Quantum Physics · Physics 2026-05-27 Sreejith Sreekumar , Ziv Goldfeld , Mark M. Wilde

In this manuscript we study the Wehrl entropy of entangled oscillators. This semiclassical entropy associated with the phase-space description of quantum mechanics can be used for formulating uncertainty relations and for a quantification…

The von Neumann entropy for an electron in periodic, disorder and quasiperiodic quantum small-world networks(QSWNs) are studied numerically. For the disorder QSWNs, the derivative of the spectrum averaged von Neumann entropy is maximal at a…

Quantum Physics · Physics 2009-09-29 Longyan Gong , Peiqing Tong

In this paper we analyze the entropy and entropy production of a non-isolated quantum system described within the quantum Brownian motion framework. This is a very general and paradigmatic framework for describing non-isolated quantum…

Statistical Mechanics · Physics 2020-09-09 G. A. Weiderpass , A. O. Caldeira

We consider the von Neumann entropy of a thermal mixed state in quantum systems derived from mirror curves, where the kinetic terms are exponential functions of the momentum operators. Using the mathematical results on the asymptotics of…

High Energy Physics - Theory · Physics 2023-10-10 Min-xin Huang

For a quantum state undergoing unitary Schr\"odinger time evolution, the von Neumann entropy is constant. Yet the second law of thermodynamics, and our experience, show that entropy increases with time. Ingarden introduced the quantum…

Quantum Physics · Physics 2019-07-03 Craig S. Lent

We introduce a measure of quantum non-Gaussianity (QNG) for those quantum states not accessible by a mixture of Gaussian states in terms of quantum relative entropy. Specifically, we employ a convex-roof extension using all possible…

Quantum Physics · Physics 2019-07-26 Jiyong Park , Jaehak Lee , Kyunghyun Baek , Se-Wan Ji , Hyunchul Nha

For a quantum channel of additive Gaussian noise with loss, in the general case of $n$ copies input, we show that up to first order perturbation, any non-Gaussian perturbation to the product thermal state input has a less quantum…

Quantum Physics · Physics 2007-10-03 Xiao-yu Chen

The von Neumann entropy of various quantum dissipative models is calculated in order to discuss the entanglement properties of these systems. First, integrable quantum dissipative models are discussed, i.e., the quantum Brownian motion and…

Quantum Physics · Physics 2009-11-11 T. Stauber , F. Guinea

Quantum channels can be activated by a kind of channels whose quantum capacity is zero. This activation effect might be useful to overcome noise of channels by attaching other channels which can enhance the capacity of a given channel. In…

Quantum Physics · Physics 2018-07-26 Youngrong Lim , Soojoon Lee