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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 review concepts and methods associated with quantum discord and related topics. We also describe their possible connections with other aspects of quantum information and beyond, including quantum communication, quantum computation,…

Quantum Physics · Physics 2018-01-17 Anindita Bera , Tamoghna Das , Debasis Sadhukhan , Sudipto Singha Roy , Aditi Sen De , Ujjwal Sen

Quantum discord is a prominent measure of quantum correlations, playing an important role in expanding its horizon beyond entanglement. Here we provide an operational meaning of (geometric) discord, which quantifies the amount of…

Quantum Physics · Physics 2015-06-05 Satyabrata Adhikari , Subhashish Banerjee

Quantum Discord (QD) is a measure of the total quantum non-local correlations of a quantum system. The formalism of quantum discord has been applied to various two-qubit mixed states and it has been reported that there is a non-zero quantum…

Quantum Physics · Physics 2022-10-04 M. S. Ramkarthik , Devvrat Tiwari , Pranay Barkataki

Establishing quantum correlations between two remote parties by sending an information carrier is an essential step of many protocols in quantum information processing. We obtain trade-off relations between discords and coherence within a…

Quantum Physics · Physics 2022-03-25 Zhi-Xiang Jin , Xianqing Li-Jost , Shao-Ming Fei , Cong-Feng Qiao

We investigate the dynamics of quantum discord during the purification process. In the case of Werner states, it is shown that quantum discord is increased after a round of purification protocol. Furthermore, quantum mutual information and…

Quantum Physics · Physics 2013-12-10 Wei Song , Lin Chen , Ming Yang , Zhuo-Liang Cao

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

In this brief review, we discuss the role that quantum correlations, as quantified by quantum discord, play in two interesting settings. The first one is discerning which unitaries have been applied on a quantum system, by taking advantage…

Quantum Physics · Physics 2017-08-01 Mile Gu , Stefano Pirandola

Despite being one of the hallmarks of quantum physics, there is a lack of operational interpretations of quantum coherence. Here we provide an operational interpretation of coherence of a quantum system, in terms of the amount of noise that…

Quantum Physics · Physics 2017-04-10 Uttam Singh , Manabendra Nath Bera , Avijit Misra , Arun Kumar Pati

Calculation of the quantum discord requires to find the minimum of the quantum conditional entropy $S(\rho^{AB}|\{\Pi^B_{k}\})$ over all measurements on the subsystem $B$. In this paper, we provide a simple relation for the conditional…

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 discord is a measure of quantum correlations beyond the entanglement-separability paradigm. It is conceptualized by using the von Neumann entropy as a measure of disorder. We introduce a class of quantum correlation measures as…

Quantum Physics · Physics 2015-08-07 Avijit Misra , Anindya Biswas , Arun K. Pati , Aditi Sen De , Ujjwal Sen

Understanding the resource consumption in distributed scenarios is one of the main goals of quantum information theory. A prominent example for such a scenario is the task of quantum state merging where two parties aim to merge their parts…

Quantum Physics · Physics 2016-06-21 A. Streltsov , E. Chitambar , S. Rana , M. N. Bera , A. Winter , M. Lewenstein

We explore experimentally the space of two-qubit quantum correlated mixed states, including frontier ones as defined by the use of quantum discord and von Neumann entropy. Our experimental setup is flexible enough to allow for the…

Quantum Physics · Physics 2011-08-31 Andrea Chiuri , Giuseppe Vallone , Mauro Paternostro , Paolo Mataloni

Quantum discord quantifies quantum correlations beyond entanglement and assumes nonzero values, which are notoriously hard to compute, for almost all quantum states. Here we provide computable tight bounds for the quantum discord for…

Quantum Physics · Physics 2011-03-01 Sixia Yu , Chengjie Zhang , Qing Chen , C. H. Oh

Macroscopic behavior such as the lack of interference patterns has been attributed to "decoherence", a word with several possible definitions such as (1) the loss of off-diagonal density matrix elements, (2) the flow of information to the…

Quantum Physics · Physics 2015-05-30 Patrick J. Coles

We calculate the quantum discord between two free modes of a scalar field which start in a maximally entangled state and then undergo a relative, constant acceleration. In a regime where there is no distillable entanglement due to the Unruh…

Quantum Physics · Physics 2013-05-29 Animesh Datta

Quantum discord is a more general measure of quantum correlations than entanglement and has been proposed as a resource in certain quantum information processing tasks. The computation of discord is mostly confined to two-qubit systems for…

Quantum Physics · Physics 2015-06-05 Indrani Bose , Amit Kumar Pal

Quantum discord, a kind of quantum correlation, is defined as the difference between quantum mutual information and classical correlation in a bipartite system. It has been discussed so far for small systems with only a few independent…

Quantum Physics · Physics 2012-04-26 sai vinjanampathy , A. R. P. Rau

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