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Entanglement fidelity quantifies how well a quantum channel preserves the correlations between a transmitted system and an inaccessible reference system. We derive closed-form expressions for the entanglement fidelity associated with…

Quantum Physics · Physics 2026-03-10 Niccolò Zanieri , Marios Kountouris

For a given ensemble of input and target states, the classical fidelity threshold (CFT) is the maximum valve of the averaged fidelity, and it can be achieved with a measure-and-prepare operation. This quantity can be employed to verify…

Quantum Physics · Physics 2018-07-17 Long Huang , Xiaohua Wu , Tao Zhou

One of the most challenging open problems in quantum information theory is to clarify and quantify how entanglement behaves when part of an entangled state is sent through a quantum channel. Of central importance in the description of a…

Quantum Physics · Physics 2007-05-23 Frank Verstraete , Henri Verschelde

We derive exact analytical expressions for the quantum capacity of a broad subclasses of generalized dephasing channels of the form $\Lambda(\rho)=(1-x)\rho + x D(\rho)$, where $D(\rho)$ represents a structured decoherence process. These…

Quantum Physics · Physics 2025-11-26 Shayan Roofeh , Vahid Karimipour

We show that the following nontrivial necessary precondition for an entanglement evolution equation for pure Gaussian states under one-sided Gaussian channels holds. Suppose a Gaussian quantum channel acts on one mode of a pure entangled…

Quantum Physics · Physics 2010-01-14 Jason Hoelscher-Obermaier , Peter van Loock

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

Entanglement-breaking channels (equivalently, measure-and-prepare channels) are an important class of quantum operations noted for their ability to destroy multipartite spatial quantum correlations. Inspired by this property, they have also…

Quantum Physics · Physics 2025-12-22 Lucas B. Vieira , Huan-Yu Ku , Costantino Budroni

Let $\Phi$ be a unital completely positive (UCP) map on the space of operators on some Hilbert space. We assume that $\Phi$ is $\eta$-idempotent, namely, $\|\Phi^2-\Phi\|_{\mathrm{cb}} \le\eta$, and construct an associated…

Operator Algebras · Mathematics 2025-02-12 Alexei Kitaev

Entanglement breaking channels play a significant role in quantum information theory. In this work we investigate qubit channels through their property of `non-locality breaking', defined in a natural way but within the purview of CHSH…

Quantum Physics · Physics 2014-10-30 Rajarshi Pal , Sibasish Ghosh

Entanglement-breaking channels are quantum channels transforming entangled states to separable states. Despite a detailed discussion of their operational structure, to be found in the literature, studies on dynamical characteristics of this…

Quantum Physics · Physics 2023-03-08 Fattah Sakuldee , Łukasz Rudnicki

Quantum channels breaking entanglement, incompatibility, or nonlocality are defined as such because they are not useful for entanglement-based, one-sided device-independent, or device-independent quantum information processing,…

The set of Entanglement Saving (ES) quantum channels is introduced and characterized. These are completely positive, trace preserving transformations which when acting locally on a bipartite quantum system initially prepared into a…

Quantum Physics · Physics 2016-05-24 Ludovico Lami , Vittorio Giovannetti

We study the regularized average Renyi output entropy $\bar{S}_{r}^{\reg}$ of quantum channels. This quantity gives information about the average noisiness of the channel output arising from a typical, highly entangled input state in the…

Quantum Physics · Physics 2015-05-28 Christopher King , David K. Moser

We consider the important class of quantum operations (completely positive trace-preserving maps) called entanglement breaking channels. We show how every such channel induces stochastic matrix representations that have the same non-zero…

Quantum Physics · Physics 2021-09-06 Jennifer Ahiable , David W. Kribs , Jeremy Levick , Rajesh Pereira , Mizanur Rahaman

Originated from the superposition principle in quantum mechanics, coherence has been extensively studied as a kind important resource in quantum information processing. We investigate the distinguishability of coherence-breaking channels…

Quantum Physics · Physics 2019-09-04 Long-Mei Yang , Tao Li , Shao-Ming Fei , Zhi-Xi Wang

Let $(M,\tau)$ be a tracial von Neumann algebra with a separable predual and let $(\Omega, \mathbb{P})$ be a probability space. A bounded positive random linear operator on $L^1(M,\tau)$ is a map $\gamma : \Omega \times L^1(M,\tau) \to…

Operator Algebras · Mathematics 2025-07-11 Brent Nelson , Eric B. Roon

In this paper we give a general integral representation for separable states in the tensor product of infinite dimensional Hilbert spaces and provide the first example of separable states that are not countably decomposable. We also prove…

Quantum Physics · Physics 2011-11-09 A. S. Holevo , M. E. Shirokov , R. F. Werner

A proper quantum memory is argued to consist in a quantum channel which cannot be simulated with a measurement followed by classical information storage and a final state preparation, i.e. an entanglement breaking (EB) channel. The…

Quantum Physics · Physics 2023-11-17 Paolo Abiuso

The generic behavior of quantum systems has long been of theoretical and practical interest. Any quantum process is represented by a sequence of quantum channels. We consider general ergodic sequences of stochastic channels with arbitrary…

Quantum Physics · Physics 2022-07-08 Ramis Movassagh , Jeffrey Schenker

We introduce a 3-parameter class of maps acting on a bipartite system that are a natural generalisation of the depolarizing channel (and include it as a special case). Then, we find the exact regions of the parameter space that…

Quantum Physics · Physics 2017-06-02 Ludovico Lami , Marcus Huber