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In this paper, in terms of the relation between the state and the reduced states of it, we obtain two inequalities which are valid for all separable states in infinite-dimensional bipartite quantum systems. One of them provides an…

Quantum Physics · Physics 2013-04-19 Yu Guo , Jinchuan Hou

We study coordination under restricted information, where classical local models fail to implement certain correlated distributions because agents cannot condition on past history. We show that quantum systems overcome this limitation even…

Quantum Physics · Physics 2026-05-08 Faisal Shah Khan

Quantum discord quantifies non-classical correlations in a quantum system including those not captured by entanglement. Thus, only states with zero discord exhibit strictly classical correlations. We prove that these states are negligible…

Quantum Physics · Physics 2015-05-14 A. Ferraro , L. Aolita , D. Cavalcanti , F. M. Cucchietti , A. Acin

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…

Not all quantum protocols require entanglement to outperform their classical alternatives. The nonclassical correlations that lead to this quantum advantage are conjectured to be captured by quantum discord. Here we demonstrate that discord…

We have analytically calculated the quantum discord for a system composed of spin-$j$ and spin-1/2 subsystems possessing SU(2) symmetry. We have compared our results with the quantum discord of states having similar symmetries and seen that…

Quantum Physics · Physics 2013-11-05 B. Çakmak , Z. Gedik

Quantum entanglement is the quantum information processing resource. Thus it is of importance to understand how much of entanglement particular quantum states have, and what kinds of laws entanglement and also transformation between…

Quantum Physics · Physics 2007-05-23 Toshiyuki Shimono

Distributed quantum information processing is a promising platform for scaling up quantum information processing, where small- and intermediate-scale quantum devices are connected by a network of quantum channels for communicating quantum…

Quantum Physics · Physics 2019-03-26 Hayata Yamasaki

Entanglement does not describe all quantum correlations and several authors have shown the need to go beyond entanglement when dealing with mixed states. Various different measures have sprung up in the literature, for a variety of reasons,…

Quantum Physics · Physics 2023-01-23 Aharon Brodutch , Kavan Modi

Multipartite entangled states possess a number of non-intuitive properties, making them a useful resource for various quantum information-processing tasks. The three-qubit W-state is one such example where every state is robust to…

Quantum Physics · Physics 2026-01-01 Souvik Chatterjee , Prasenjit Deb , Chandan Datta , Pankaj Agrawal

We consider the separability of various joint states of D-dimensional quantum systems, which we call "qudits." We derive two main results: (i) the separability condition for a two-qudit state that is a mixture of the maximally mixed state…

Quantum Physics · Physics 2012-01-04 P. Rungta , W. J. Munro , K. Nemoto , P. Deuar , G. J. Milburn , C. M. Caves

We study experimentally accessible lower bounds on entanglement measures based on entropic uncertainty relations. Experimentally quantifying entanglement is highly desired for applications of quantum simulation experiments to fundamental…

Quantum Physics · Physics 2021-05-25 Bjarne Bergh , Martin Gärttner

We propose a framework to characterize entanglement with quantum discord, both asymmetric and symmetric, over state extensions. In particular, we show that the minimal Bures distance of discord over state extensions is equivalent to Bures…

Quantum Physics · Physics 2022-01-27 Chunhe Xiong , Sunho Kim , Daowen Qiu , Asutosh Kumar , Junde Wu

We investigate entanglement distribution in pure-state quantum networks. We consider the case when non-maximally entangled two-qubit pure states are shared by neighboring nodes of the network. For a given pair of nodes, we investigate how…

Quantum Physics · Physics 2009-01-19 S. Perseguers , J. Wehr , A. Acin , M. Lewenstein , J. I. Cirac

The entanglement swapping protocol (ESP) is a fundamental primitive for distributing quantum correlations across distant nodes in a quantum network. Recent studies have demonstrated that even when the involved qubit pairs are only partially…

Quantum Physics · Physics 2026-03-24 Henrique Guerra , Tailan S. Sarubi , Rafael Chaves , Jonas Maziero

Entanglement, or quantum inseparability, is a crucial resource in quantum information applications, and therefore the experimental generation of separated yet entangled systems is of paramount importance. Experimental demonstrations of…

Quantum Physics · Physics 2009-11-07 M. G. Raymer , A. C. Funk , B. C. Sanders , H. de Guise

We address the question of the role of quantum correlations beyond entanglement in context of quantum magnetometry. To this end, we study the evolution of the quantum discord, measured by the rescaled discord, of two electron-spin qubits…

Quantum Physics · Physics 2015-06-12 Paweł Mazurek , Katarzyna Roszak , Paweł Horodecki

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

Entangled physical systems are an important resource in quantum information. Some authors claim that in fact all quantum states are entangled. In this paper we show that this claim is incorrect and we discuss in operational way differences…

Quantum Physics · Physics 2016-10-07 Marian Kupczynski

This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many…

Quantum Physics · Physics 2008-08-12 Hyeyoun Chung