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In this work we aim at quantifying quantum channel output similarity. In order to achieve this, we introduce the notion of quantum channel superfidelity, which gives us an upper bound on the quantum channel fidelity. This quantity is…

Quantum Physics · Physics 2018-10-12 Łukasz Pawela , Zbigniew Puchała

We consider a class (convex set) of quantum states containing all finite rank states and infinite rank states with the sufficient rate of decreasing of eigenvalues (in particular, all Gaussian states). Quantum states from this class are…

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

The maximum entropy principle, as applied to quantum systems, is a fundamental prescript positing that for a quantum system for which we only have partial knowledge, the maximum entropy state consistent with the partial knowledge is a…

Quantum Physics · Physics 2025-07-24 Siddhartha Das , Ujjwal Sen

We examine the chaotic behavior of certain continuous linear operators on infinite-dimensional Banach spaces, and provide several equivalent characterizations of when these operators have infinite topological entropy. For example, it is…

Dynamical Systems · Mathematics 2019-08-02 Will Brian , James P. Kelly

The quantum relative entropy is frequently used as a distance, or distinguishability measure between two quantum states. In this paper we study the relation between this measure and a number of other measures used for that purpose,…

Quantum Physics · Physics 2009-11-11 K. M. R. Audenaert , J. Eisert

We prove an entropic uncertainty relation for two quantum channels, extending the work of Frank and Lieb for quantum measurements. This is obtained via a generalized strong super-additivity (SSA) of quantum entropy. Motivated by Petz's…

Quantum Physics · Physics 2023-01-23 Li Gao , Marius Junge , Nicholas LaRacuente

Uniform continuity bounds on entropies are generally expressed in terms of a single distance measure between a pair of probability distributions or quantum states, typically, the total variation distance or trace distance. However, if an…

Quantum Physics · Physics 2025-01-09 Michael G. Jabbour , Nilanjana Datta

The irreversible motion of an open quantum system can be represented through an ensemble of state vectors following a stochastic dynamics with piecewise deterministic paths. It is shown that this representation leads to a natural definition…

Quantum Physics · Physics 2007-05-23 Heinz-Peter Breuer

The continuity properties of the convex closure of the output entropy of infinite dimensional channels and their applications to the additivity problem are considered. The main result of this paper is the statement that the superadditivity…

Quantum Physics · Physics 2008-12-17 M. E. Shirokov

Capacities of quantum channels are fundamental quantities in the theory of quantum information. A desirable property is the additivity for a capacity. However, this cannot be achieved for a few quantities that have been established as…

Quantum Physics · Physics 2025-05-20 D. -S. Wang

In this work we examine quantum states which have non-negative amplitudes (in a fixed basis) and the channels which preserve them. These states include the ground states of stoquastic Hamiltonians and they are of interest since they avoid…

Quantum Physics · Physics 2022-09-08 Nathaniel Johnston , Jamie Sikora

We analyze the quality of the quantum information transmission along a correlated quantum channel by studying the average fidelity between input and output states and the average output purity, giving bounds for the entropy of the channel.…

Quantum Physics · Physics 2008-11-26 Davide Rossini , Vittorio Giovannetti , Simone Montangero

An analogue of the mixing property of quantum entropy is derived for quantum relative entropy.It is applied to the final state of ideal measurement and to the spectral form of the second density operator. Three cases of states on a directed…

Quantum Physics · Physics 2007-05-23 Fedor Herbut

In this work, we study two different approaches to defining the entropy of a quantum channel. One of these is based on the von Neumann entropy of the corresponding Choi-Jamio{\l}kowski state. The second one is based on the relative entropy…

Quantum Physics · Physics 2021-08-17 Dariusz Kurzyk , Łukasz Pawela , Zbigniew Puchała

In this work, we study the stochastic entropy production in open quantum systems whose time evolution is described by a class of non-unital quantum maps. In particular, as in [Phys. Rev. E 92, 032129 (2015)], we consider Kraus operators…

Quantum Physics · Physics 2023-06-21 Eliana Fiorelli , Stefano Gherardini , Stefano Marcantoni

In this paper we give a simple sequence of necessary and sufficient finite dimensional conditions for a positive map between certain subspaces of bounded linear operators on separable Hilbert spaces to be completely positive. These…

Operator Algebras · Mathematics 2018-07-09 Shmuel Friedland

We formalize the correspondence between quantum states and quantum operations isometrically, and harness its consequences. This correspondence was already implicit in the various proofs of the operator sum representation of Completely…

Quantum Physics · Physics 2009-11-10 Pablo Arrighi , Christophe Patricot

Counter-intuitive to classical notions, quantum conditional entropy can be negative, playing a pivotal role in information-processing tasks. This article delves deeply into quantum channels, emphasizing negative conditional entropy breaking…

Quantum Physics · Physics 2024-11-06 PV Srinidhi , Indranil Chakrabarty , Samyadeb Bhattacharya , Nirman Ganguly

We establish the general framework of quantum fluctuation theorems by finding the symmetry between the forward and backward transitions of any given quantum channel. The Petz recovery map is adopted as the reverse quantum channel, and the…

Quantum Physics · Physics 2019-08-23 Hyukjoon Kwon , M. S. Kim

Environmental interactions are ubiquitous in any real-world application of a quantum information processing protocol. Such interactions result in depletion of quantum resources. Two important figure of merits in the context of quantum…

Quantum Physics · Physics 2024-06-06 Tapaswini Patro , Kaushiki Mukherjee , Nirman Ganguly