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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

We present observable lower and upper bounds for the entanglement of formation (EOF) and quantum discord (QD), which facilitates estimates of EOF and QD for arbitrary experimental unknown states in finite-dimensional bipartite systems.…

Quantum Physics · Physics 2015-05-28 Chengjie Zhang , Sixia Yu , Qing Chen , C. H. Oh

To quantify the entanglement is one of the most important topics in quantum entanglement theory. In [arXiv: 2006.12408], the authors proposed a method to build a measure from the orginal domain to a larger one. Here we apply that method to…

Quantum Physics · Physics 2021-04-21 Xian Shi , Lin Chen

We propose a novel parameterized entanglement measure $\alpha$-concurrence for bipartite systems. By employing positive partial transposition and realignment criteria, we derive analytical lower bounds for the $\alpha$-concurrence.…

Quantum Physics · Physics 2022-06-17 Zhi-Wei Wei , Shao-Ming Fei

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…

While entanglement plays an important role in characterizing quantum many-body systems, it is hardly possible to directly access many-body entanglement in real experiments. In this paper, we study how bipartite entanglement of many-body…

Quantum Physics · Physics 2018-07-11 Chae-Yeun Park , Jaeyoon Cho

Entanglement is not only the resource that fuels many quantum technologies but also plays a key role for some of the most profound open questions of fundamental physics. Experiments controlling quantum systems at the single quantum level…

Quantum Physics · Physics 2021-06-02 Bjarne Bergh , Martin Gärttner

Amount of entanglement carried by a quantum bipartite state is usually evaluated in terms of concurrence (see Ref. 1). We give a physical interpretation of concurrence that reveals a way of its direct measurement and discuss possible…

Quantum Physics · Physics 2016-08-16 Alexander Klyachko , Barış Öztop , Alexander S. Shumovsky

We study the concurrence of arbitrary dimensional bipartite quantum systems. An explicit analytical lower bound of concurrence is obtained, which detects entanglement for some quantum states better than some well-known separability…

Quantum Physics · Physics 2011-04-07 Xiao-Sheng Li , Xiu-Hong Gao , Shao-Ming Fei

I give an overview of some of the most used measures of entanglement. To make the presentation self-contained, a number of concepts from quantum information theory are first explained. Then the structure of bipartite entanglement is studied…

Quantum Physics · Physics 2007-05-23 Geir Ove Myhr

We study the quantification of genuine multipartite entanglement (GME) for general multipartite states. A set of inequalities satisfied by the entanglement of $N$-partite pure states is derived by exploiting the restrictions on entanglement…

Quantum Physics · Physics 2022-12-15 Zhi-Xiang Jin , Yuan-Hong Tao , Yao-Ting Gui , Shao-Ming Fei , Xianqing Li-Jost , Cong-Feng Qiao

We investigate upper and lower bounds on the entropy of entanglement of a superposition of bipartite states as a function of the individual states in the superposition. In particular, we extend the results in [G. Gour, arxiv.org:0704.1521…

Quantum Physics · Physics 2009-11-13 Gilad Gour , Aidan Roy

A relevant problem regarding entanglement measures is the following: Given an arbitrary mixed state, how does a measure for multipartite entanglement change if general local operations are applied to the state? This question is nontrivial…

Quantum Physics · Physics 2015-05-30 Oliver Viehmann , Christopher Eltschka , Jens Siewert

While the experimental detection of entanglement provides already quite a difficult task, experimental quantification of entanglement is even more challenging, and has not yet been studied thoroughly. In this paper we discuss several issues…

Quantum Physics · Physics 2009-11-25 Remigiusz Augusiak , Maciej Lewenstein

The entanglement detection via local measurements can be experimentally implemented. Based on mutually unbiased measurements and general symmetric informationally complete positive-operator-valued measures, we present separability criteria…

Quantum Physics · Physics 2018-03-30 Shu-Qian Shen , Ming Li , Xianqing Li-Jost , Shao-Ming Fei

For a tripartite pure state superposed by two individual states, the bipartitely shared entanglement can always be achieved by local measurements of the third party. Consider the different aims of the third party, i.e. maximizing or…

Quantum Physics · Physics 2009-11-13 Chang-shui Yu , X. X. Yi , He-shan Song

Entanglement of formation quantifies the entanglement of a state in terms of the entropy of entanglement of the least entangled pure state needed to prepare it. An analytical expression for this measure exists only for special cases, and…

Quantum Physics · Physics 2019-05-29 Spyros Tserkis , Sho Onoe , Timothy C. Ralph

Genuine-multipartite-entanglement (GME) concurrence is a measure of genuine multipartite entanglement that generalizes the well-known notion of concurrence. We define an observable for GME concurrence. The observable permits us to avoid…

Quantum Physics · Physics 2012-09-26 Zhi-Hua Chen , Zhi-Hao Ma , Jing-Ling Chen , Simone Severini

Numerous work had been done to quantify the entanglement of a two-qubit quantum state, but it can be seen that previous works were based on joint measurements on two copies or more than two copies of a quantum state under consideration. In…

Quantum Physics · Physics 2019-01-04 Satyabrata Adhikari

Entanglement measures quantify nonclassical correlations present in a quantum system, but can be extremely difficult to calculate, even more so, when information on its state is limited. Here, we consider broad families of entanglement…

Quantum Physics · Physics 2021-07-07 Matteo Fadel , Ayaka Usui , Marcus Huber , Nicolai Friis , Giuseppe Vitagliano