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A remarkable feature of quantum entanglement is that an entangled state of two parties, Alice (A) and Bob (B), may be more disordered locally than globally. That is, S(A) > S(A,B), where S(.) is the von Neumann entropy. It is known that…

Quantum Physics · Physics 2009-11-06 M. A. Nielsen , J. Kempe

Quantum nonlocality is usually associated with entangled states by their violations of Bell-type inequalities. However, even unentangled systems, whose parts may have been prepared separately, can show nonlocal properties. In particular, a…

Quantum Physics · Physics 2019-02-06 Saronath Halder , Manik Banik , Sristy Agrawal , Somshubhro Bandyopadhyay

Bell nonlocality is a valuable resource in quantum information processing tasks. Scientists are interested in whether a single entangled state can generate a long sequence of nonlocal correlations. Previous work has accomplished sequential…

Quantum Physics · Physics 2024-06-27 Yiyang Xu , Hao Sun , Fenzhuo Guo , Haifeng Dong , Qiaoyan Wen

A set of orthogonal multipartite quantum states is said to be distinguishability-based genuinely nonlocal (also genuinely nonlocal, for abbreviation) if the states are locally indistinguishable across any bipartition of the subsystems. This…

Quantum Physics · Physics 2023-11-22 Zong-Xing Xiong , Mao-Sheng Li , Zhu-Jun Zheng , Lvzhou Li

We investigate some basic scenarios in which a given set of bipartite quantum states may consistently arise as the set of reduced states of a global N-partite quantum state. Intuitively, we say that the multipartite state "joins" the…

Quantum Physics · Physics 2013-09-30 Peter D. Johnson , Lorenza Viola

Local distinguishability of orthogonal product states is an area of active research in quantum information theory. However, most of the relevant results about local distinguishability found in bipartite quantum systems and very few are…

Quantum Physics · Physics 2025-08-21 Atanu Bhunia , Indrani Chattopadhyay , Debasis Sarkar

We show that any Bell local state, with a hidden nonlocality that can be revealed by local filtering, is more, or equally, entangled than nonlocal states. More precisely, it can be deterministically transformed into a nonlocal state, by…

Quantum Physics · Physics 2017-12-06 S. Camalet

One of the many interesting features of quantum nonlocality is that the states of a multipartite quantum system cannot always be distinguished as well by local measurements as they can when all quantum measurements are allowed. In this…

Quantum Physics · Physics 2013-11-14 Somshubhro Bandyopadhyay , Michael Nathanson

The question whether global entanglement of a multiparticle quantum system can be inferred from local properties is of great relevance for the theory of quantum correlations as well as for experimental implementations. We present a method…

Quantum Physics · Physics 2016-03-02 Nikolai Miklin , Tobias Moroder , Otfried Gühne

Standard tripartite nonlocality and genuine tripartite nonlocality can be detected by the violations of Mermin inequality and Svetlichny inequality, respectively. Since tripartite quantum nonlocality has novel applications in quantum…

Sharing genuine multipartite entanglement by considering collective use of copies of biseparable states, which are entangled across all bipartitions but lack genuine multipartite entanglement at the single-copy level, plays a central role…

Quantum Physics · Physics 2026-01-26 Swati Choudhary , Ujjwal Sen , Saronath Halder

We investigate separability and entanglement of mixed states in ${\cal C}^2\otimes{\cal C}^2\otimes{\cal C}^N$ three party quantum systems. We show that all states with positive partial transposes that have rank $\le N$ are separable. For…

Quantum Physics · Physics 2009-11-07 S. Karnas , M. Lewenstein

We consider Bell tests involving bipartite states shared between three parties. We show that the simple inclusion of a third part may greatly simplify the measurement scenario (in terms of the number of measurement settings per part) and…

Quantum Physics · Physics 2012-01-26 Daniel Cavalcanti , Rafael Rabelo , Valerio Scarani

As a striking manifestation of quantum entanglement, nonlocality has long played a pivotal role in shaping our understanding of the quantum world. When considering a Bell test involving three parties, we may even find a remarkable situation…

Quantum Physics · Physics 2026-04-10 Kai-Siang Chen , Gelo Noel M. Tabia , Chung-Yun Hsieh , Yu-Chun Yin , Yeong-Cherng Liang

In this letter we prove local indistinguishability of four orthogonal activable bound entangled states shared among even number of parties. All reduced density matrices of such states are maximally mixed. We further proceed to establish a…

Quantum Physics · Physics 2009-11-13 Indrani Chattopadhyay , Debasis Sarkar

We qualify the entanglement of arbitrary mixed states of bipartite quantum systems by comparing global and marginal mixednesses quantified by different entropic measures. For systems of two qubits we discriminate the class of maximally…

Quantum Physics · Physics 2007-05-23 Gerardo Adesso , Fabrizio Illuminati , Silvio De Siena

We show that all $n$-qubit entangled states, with the exception of tensor products of single-qubit and bipartite maximally-entangled states, admit Hardy-type proofs of non-locality without inequalities or probabilities. More precisely, we…

Quantum Physics · Physics 2017-02-22 Samson Abramsky , Carmen M. Constantin , Shenggang Ying

In a multipartite setting, it is possible to distinguish quantum states that are genuinely $n$-way entangled from those that are separable with respect to some bipartition. Similarly, the nonlocal correlations that can arise from…

Quantum Physics · Physics 2013-07-24 Jean-Daniel Bancal , Jonathan Barrett , Nicolas Gisin , Stefano Pironio

We consider a general version of the phenomenon of more nonlocality with less entanglement, within the framework of the unambiguous (i.e., conclusive) quantum state discrimination problem under local quantum operations and classical…

Quantum Physics · Physics 2022-03-25 Saronath Halder , Ujjwal Sen

Recently, Halder \emph{et al.} [Phys. Rev. Lett. \textbf{122}, 040403 (2019)] proposed the concept strong nonlocality without entanglement: an orthogonal set of fully product states in multipartite quantum systems that is locally…

Quantum Physics · Physics 2021-10-27 Mao-Sheng Li , Yan-Ling Wang , Fei Shi , Man-Hong Yung