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We give an explicit tight lower bound for the entanglement of formation for arbitrary bipartite mixed states by using the convex hull construction of a certain function. This is achieved by revealing a novel connection among the…

Quantum Physics · Physics 2007-05-23 Kai Chen , Sergio Albeverio , Shao-Ming Fei

We study the entanglement of multipartite quantum states. Some lower bounds of the multipartite concurrence are reviewed. We further present more effective lower bounds for detecting and qualifying entanglement, by establishing functional…

Quantum Physics · Physics 2015-06-05 Xue-Na Zhu , Ming Li , Shao-Ming Fei

Entanglement monotones, such as the concurrence, are useful tools to characterize quantum correlations in various physical systems. The computation of the concurrence involves, however, difficult optimizations and only for the simplest case…

Quantum Physics · Physics 2012-11-20 Zhi-Hua Chen , Zhi-Hao Ma , Otfried Gühne , Simone Severini

In this paper we consider a system consist of a qubit and a qutrit, and find a formula to evaluate the concurrence for it. We show that entanglement of formation for this system obeys the same relation as for two-qubits.

Quantum Physics · Physics 2007-05-23 Safa Jami , Mohsen Sarbishei

The concurrence, a quantitative measure of the entanglement between a pair of particles, is determined for the case where the pair is extracted from a symmetric state of N two-level systems. Examples are given for both pure and mixed states…

Quantum Physics · Physics 2009-11-07 Xiaoguang Wang , Klaus Molmer

We study the role of average concurrence in entanglement swapping in quantum networks. We begin with qubit pure states, and there is a very simple rule governing the propagation of average concurrence in multiple swaps. We look at examples…

Quantum Physics · Physics 2021-09-01 János A. Bergou , Dov Fields , Mark Hillery , Siddhartha Santra , Vladimir S. Malinovsky

We present the generalization of the entanglement of formation for three-party systems in a pure state. For three qubit system we derive out its explicit and closed expression which is a linear combination of the binary entropy functions…

Quantum Physics · Physics 2007-05-23 An Min Wang

Quantum entanglement is a crucial resource in quantum information processing, advancing quantum technologies. The greater the uncertainty in subsystems' pure states, the stronger the quantum entanglement between them. From the dual form of…

Quantum Physics · Physics 2026-01-01 Dong-Ping Xuan , Zhong-Xi Shen , Wen Zhou , Zhi-Xi Wang , Shao-Ming Fei

We derive a lower bound for the concurrence of mixed bipartite quantum states, valid in arbitrary dimensions. As a corollary, a weaker, purely algebraic estimate is found, which detects mixed entangled states with positive partial…

Quantum Physics · Physics 2009-11-10 Florian Mintert , Marek Kus , Andreas Buchleitner

We derive an explicit analytic estimate for the entanglement of a large class of bipartite quantum states which extends into bound entanglement regions. This is done by using an efficiently computable concurrence lower bound, which is…

We study the entanglement of a multipartite quantum state. An inequality between the bipartite concurrence and the multipartite concurrence is obtained. More effective lower and upper bounds of the multipartite concurrence are obtained. By…

Quantum Physics · Physics 2015-05-19 Ming Li , Shao-Ming Fei , Zhi-Xi Wang

While the detection of entanglement has been proved already to be quite a difficult task, experimental quantification of entanglement is even more challenging. In this work, we derive an analytical lower bound for the concurrence of a…

Quantum Physics · Physics 2011-04-07 Zhi-Hao Ma , Zhi-Hua Chen , Jing-Ling Chen

We prove exactly that the squared entanglement of formation, which quantifies the bipartite entanglement, obeys a general monogamy inequality in an arbitrary multiqubit mixed state. Based on this kind of exotic monogamy relation, we are…

Quantum Physics · Physics 2014-09-10 Yan-Kui Bai , Yuan-Fei Xu , Z. D. Wang

We study entanglement and other correlation properties of random states in high-dimensional bipartite systems. These correlations are quantified by parameters that are subject to the "concentration of measure" phenomenon, meaning that on a…

Quantum Physics · Physics 2007-05-23 Patrick Hayden , Debbie W. Leung , Andreas Winter

Quantification of quantum entanglement plays a crucial role in the study of quantum information tasks. We present analytical lower bounds for both concurrence and 2-concurrence based on the correlation matrices of bipartite quantum states.…

Quantum Physics · Physics 2025-03-21 Zhi-Bo Chen , Shao-Ming Fei

Entanglement is a unique nature of quantum theory and has tremendous potential for application. Nevertheless, the complexity of quantum entanglement grows exponentially with an increase in the number of entangled particles. Here we…

Quantum Physics · Physics 2018-01-17 S. M. Zangi , Jun-Li Li , Cong-Feng Qiao

A simplified expression of concurrence for two-qubit mixed state having no more than three non-vanishing eigenvalues is obtained. Basing on SU(2) coherent states, the amount of entanglement of two-qubit pure states is studied and conditions…

Quantum Physics · Physics 2012-04-06 S. Salimi , A. Mohammadzade , K. Berrada

Concurrence is an important entanglement measure for states in finite-dimensional quantum systems that was explored intensively in the last decade. In this paper, we extend the concept of concurrence to infinite-dimensional bipartite…

Quantum Physics · Physics 2012-03-20 Yu Guo , Jinchuan Hou , Yuncai Wang

Monogamy of entanglement is generally discussed using a bipartite entanglement measure as an upper bound. Here we discuss a new kind of monogamous relation where the upper bound is given by a multipartite measure of entanglement, the…

Quantum Physics · Physics 2013-03-27 Marcio F. Cornelio

Entanglement of formation is a fundamental measure that quantifies the entanglement of bipartite quantum states. This measure has recently been extended into multipartite states taking the name $\alpha$-entanglement of formation. In this…

Quantum Physics · Physics 2020-10-28 Sho Onoe , Spyros Tserkis , Austin P. Lund , Timothy C. Ralph