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Quantum discord (QD) reveals the nonclassical nature of correlations in bipartite quantum states, going beyond the entanglement-separability paradigm. In this article we discuss the suitability of QD in what concern its possible asymmetry…

Quantum Physics · Physics 2015-03-14 J. Maziero , L. C. Celeri , R. M. Serra

We investigated the super quantum discord based on weak measurements. The super quantum discord is an extension of the standard quantum discord defined by projective measurements and also describes the quantumness of correlations. We…

Quantum Physics · Physics 2014-04-02 Bo Li , Lin Chen , Heng Fan

We report investigation on quantum discord in classical second-order interference. In particular, we theoretically show that a bipartite state with D = 0.311 of discord can be generated via classical second-order interference. We also…

The "classical-quantum" ($\mathit{cq}$) discord of a bipartite state $\rho^{AB}$ is the smallest difference between the mutual information $S(\rho^{A:B})$ of $\rho$ and that of $\rho$ after a measurement channel is applied on the $A$…

Quantum Physics · Physics 2016-08-30 Michel Boyer

Quantum discord plays a pragmatic role in analyzing nonclassical feature of quantum correlations beyond entanglement. It is used in several information processing protocols which lacks sufficient amount of entanglement to be used as a…

Quantum Physics · Physics 2019-10-02 Kaushiki Mukherjee , Sumana Karmakar , Biswajit Paul , Debasis Sarkar

We study the relative strength of classical and quantum correlations, as measured by discord, for two-qubit states. Quantum correlations appear only in the presence of classical correlations, while the reverse is not always true. We…

Quantum Physics · Physics 2011-01-17 Fernando Galve , Gian Luca Giorgi , Roberta Zambrini

Measurements of Quantum Systems disturb their states. To quantify this non-classical characteristic, Zurek and Ollivier introduced the quantum discord, a quantum correlation which can be nonzero even when entanglement in the system is zero.…

Quantum Physics · Physics 2010-07-13 Asma Al-Qasimi , Daniel F. V. James

Open quantum systems have attracted great attention, since inevitable coupling between quantum systems and their environment greatly affects the features of interest of these systems. Quantum discord, is a measure of the total nonclassical…

Quantum Physics · Physics 2012-11-30 Jin-Shi Xu , Chuan-Feng Li

Quantum Darwinism builds on decoherence theory to explain the emergence of classical behavior in a fundamentally quantum universe. Within this framework we prove two crucial insights about the emergence of classical phenomenology, centered…

Quantum Physics · Physics 2024-10-16 Akram Touil , Fabio Anza , Sebastian Deffner , James P. Crutchfield

In quantum information theory, quantum discord has been proposed as a tool to characterise the presence of "quantum correlations" between the subparts of a given system. Whether a system behaves quantum-mechanically or classically is…

Quantum Physics · Physics 2022-10-20 Jerome Martin , Amaury Micheli , Vincent Vennin

Recently, it was realized that quantum discord can be seen as the minimal amount of correlations which are lost when some local quantum operations are performed. Based on this formulation of quantum discord, we provide a systematical…

Quantum Physics · Physics 2011-12-21 Małgorzata Okrasa , Zbigniew Walczak

We introduce the notion of quantum dissension for a three-qubit system as a measure of quantum correlations. We use three equivalent expressions of three-variable mutual information. Their differences can be zero classically but not so in…

Quantum Physics · Physics 2012-04-05 Indranil Chakrabarty , Pankaj Agrawal , Arun K. Pati

We introduce a simple and efficient technique to verify quantum discord in unknown Gaussian states and a certain class of non-Gaussian states. We show that any separation in the peaks of the marginal distributions of one subsystem…

Discordant states appear in a large number of quantum phenomena and seem to be a good indicator of divergence from classicality. While there is evidence that they are essential for a quantum algorithm to have an advantage over a classical…

Quantum Physics · Physics 2013-10-04 Aharon Brodutch

The positivity of quantum discord is shown to be equivalent to the strong subadditivity of von-Neumann entropy. This leads us to a necessary and sufficient condition characterizing the set of states with zero quantum discord. This also…

Quantum Physics · Physics 2011-06-21 Animesh Datta

We discuss the problem of the separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to…

Quantum Physics · Physics 2010-03-03 Kavan Modi , Tomasz Paterek , Wonmin Son , Vlatko Vedral , Mark Williamson

Discord, originally notable as a signature of bipartite quantum correlation,in fact can be nonzero classically, i.e., arising from noisy measurements by one of the two parties. Here we redefine classical discord to quantify channel…

Quantum Physics · Physics 2021-09-16 Wei-Wei Zhang , Yuval R. Sanders , Barry C. Sanders

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

Quantum systems unfold diversified correlations which have no classical counterparts. These quantum correlations have various different facets. Quantum entanglement, as the most well known measure of quantum correlations, plays essential…

Quantum discord is a measure of non-classical correlations, which are excess correlations inherent in quantum states that cannot be accessed by classical measurements. For multipartite states, the classically accessible correlations can be…

Quantum Physics · Physics 2019-09-18 Mark Bradshaw , Ping Koy Lam , Syed M. Assad