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Quantum channels describe subsystem or open system evolution. Using the classical Koopman operator that evolves functions on phase space, 4 classical Koopman channels are identified that are analogs of the 4 possible quantum channels in a…

Quantum Physics · Physics 2024-07-22 Bidhi Vijaywargia , Arul Lakshminarayan

Degradable quantum channels are among the only channels whose quantum and private classical capacities are known. As such, determining the structure of these channels is a pressing open question in quantum information theory. We give a…

Quantum Physics · Physics 2009-11-13 Toby S. Cubitt , Mary-Beth Ruskai , Graeme Smith

We connect two key concepts in quantum information: compatibility and divisibility of quantum channels. Two channels are compatible if they can be both obtained via marginalization from a third channel. A channel divides another channel if…

Quantum Physics · Physics 2022-07-27 Cristhiano Duarte , Lorenzo Catani , Raphael C. Drumond

Correlations may arise in quantum systems through various means, of which the most remarkable one is quantum entanglement. Additionally, there are systems that exhibit non-classical correlations even in the absence of entanglement. Quantum…

Quantum Physics · Physics 2024-08-13 Gökhan Torun

The coherence-breaking channels play a significant role in quantum information theory. We study the coherence-breaking channels and give a method to amend the coherence-breaking channels by applying unitary operations. For given incoherent…

Quantum Physics · Physics 2018-10-24 Long-Mei Yang , Bin Chen , Tao Li , Shao-Ming Fei , Zhi-Xi Wang

This paper summarizes the basics of the notion of quantum discord and how it relates to other types of correlations in quantum physics. We take the fundamental information theoretic approach and illustrate our exposition with a number of…

Quantum Physics · Physics 2017-02-07 Vlatko Vedral

We focus our attention on two-qubit mixed states as initial states, and apply the geometric measure of quantum discord to investigate quantum discord properties in the background of a Schwarzschild black hole under phase damping, phase flip…

Quantum Physics · Physics 2026-04-08 Yuxuan Xiong , Zhiling Pi , Tinggui Zhang , Xiaofen Huang

Quantum discord Q is a function of density matrix elements. The domain of such a function in the case of two-qubit system with X density matrix may consist of three subdomains at most: two ones where the quantum discord is expressed in…

Quantum Physics · Physics 2015-11-11 M. A. Yurischev

The non-Markovian decoherence of quantum and classical correlations is analytically obtained when two qubits are asymmetrically subjected to the bit flip channel and phase flip channel. For one class of initial mixed states, quantum…

Quantum Physics · Physics 2012-08-09 Xiang Hao , Tao Pan , Jinqiao Sha

Quantum discord goes beyond entanglement and exists in a wide range of quantum states that may be separable, playing a crucial role in quantum information tasks. In this paper, we firstly proposed a zero-discord criterion for two-qubit…

Quantum Physics · Physics 2024-08-13 Wang Yiding , Huang Xiaofen , Zhang Tinggui

Quantum masking is a special type of secret sharing in which some information gets reversibly distributed into a multipartite system, leaving the original information inaccessible to each subsystem. This paper proposes a dynamical extension…

Quantum Physics · Physics 2026-05-07 Anna Honeycutt , Hailey Murray , Eric Chitambar

We give a criterion to differentiate between dissipative and diffusive quantum operations. It is based on the classical idea that dissipative processes contract volumes in phase space. We define a quantity that can be regarded as ``quantum…

Quantum Physics · Physics 2010-03-31 Ignacio Garcia-Mata , Marcos Saraceno , Maria Elena Spina , Gabriel Carlo

Using well known duality between quantum maps and states of composite systems we introduce the notion of Schmidt number of a quantum channel. It enables one to define classes of quantum channels which partially break quantum entanglement.…

Quantum Physics · Physics 2007-05-23 Dariusz Chruscinski , Andrzej Kossakowski

The dynamics of the quantum discord for two identical qubits in both two independent single-mode cavities and a common single-mode cavity are discussed. For the initial Bell state with correlated spins, while the entanglement sudden death…

Quantum Physics · Physics 2015-06-04 Chen Wang , Qing-Hu Chen

Quantum channels represent a broad spectrum of operations crucial to quantum information theory, encompassing everything from the transmission of quantum information to the manipulation of various resources. In the domain of states, the…

Quantum Physics · Physics 2025-05-15 Gilad Gour , Doyeong Kim , Takla Nateeboon , Guy Shemesh , Goni Yoeli

In this didactic article we explore the concept of quantum correlations beyond entanglement. We begin by introducing and motivating the classically correlated states and then showing how to quantify the quantum correlations using an…

Quantum Physics · Physics 2016-11-08 Gerardo Adesso , Marco Cianciaruso , Thomas R. Bromley

We show that two qubits initially in completely classical state can create quantum discord through a local generalized amplitude damping channel, but high temperature will impede the creating of quantum discord.

Quantum Physics · Physics 2011-07-29 Jianwei Xu

Quantum discord is a measure of the quantumness of correlations. After reviewing its different versions and properties, we apply it to the questions of quantum information processing. First we show that changes in discord in the processed…

Quantum Physics · Physics 2015-03-17 Aharon Brodutch , Alexei Gilchrist , Daniel R. Terno , Christopher J. Wood

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

Quantum discord refers to an important aspect of quantum correlations for bipartite quantum systems. In our earlier works we have shown that corresponding to every graph (combinatorial) there are quantum states whose properties are…

Quantum Physics · Physics 2019-03-20 Supriyo Dutta , Bibhas Adhikari , Subhashish Banerjee