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Bell nonlocality refers to correlations between two distant, entangled particles that challenge classical notions of local causality. Beyond its foundational significance, nonlocality is crucial for device-independent technologies like…

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

Entanglement appears under two different forms in quantum theory, namely as a property of states of joint systems and as a property of measurement eigenstates in joint measurements. By combining these two aspects of entanglement, it is…

Quantum information is nonlocal in the sense that local measurements on a composite quantum system, prepared in one of many mutually orthogonal states, may not reveal in which state the system was prepared. It is shown that in the many copy…

Quantum Physics · Physics 2015-05-28 Somshubhro Bandyopadhyay

We define nonlocal predictability as how well one observer can predict another's measurement outcomes without classical communication, given full knowledge of the shared quantum state and measurement settings. The local bound on nonlocal…

Quantum Physics · Physics 2026-02-19 Chirag Srivastava , Aparajita Bhattacharyya , Ujjwal Sen

One of the most fascinating aspects of quantum networks is their capability to distribute entanglement as a nonlocal communication resource. In a first step, this requires network-ready devices that can generate and store entangled states.…

We introduce a new aspect of nonlocality which arises when the task of quantum states distinguishability is considered under local operations and shared entanglement in the absence of classical communication. We find the optimal amount of…

Quantum Physics · Physics 2016-03-24 Berry Groisman , Sergii Strelchuk

It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by quantum discord, but not by the conventional measure of entanglement. We argue that a state…

Quantum Physics · Physics 2016-09-30 Pankaj Agrawal , Sk Sazim , Indranil Chakrabarty , Arun K. Pati

We consider the optimal discrimination of nonorthogonal qubit states with post-measurement information and provide an analytic structure of the optimal measurements. We also show that there is always a null optimal measurement when…

Quantum Physics · Physics 2022-01-25 Donghoon Ha , Jeong San Kim , Younghun Kwon

Entangled systems in experiments may be lost or offline in distributed quantum information processing. This inspires a general problem to characterize quantum operations which result in breaking of entanglement or not. Our goal in this work…

Quantum Physics · Physics 2022-04-21 Ming-Xing Luo , Shao-Ming Fei

It is known that there exist sets of pure orthogonal product states which cannot be perfectly distinguished by local operations and classical communication (LOCC). Such sets are nonlocal sets which exhibit nonlocality without entanglement.…

Quantum Physics · Physics 2018-08-07 Saronath Halder

The relation between entanglement and nonlocality is discussed in the case of multipartite quantum systems. We show that, for any number of parties, there exist genuinely multipartite entangled states which admit a fully local hidden…

Quantum Physics · Physics 2016-04-06 Joseph Bowles , Jérémie Francfort , Mathieu Fillettaz , Flavien Hirsch , Nicolas Brunner

Quantum nonlocality offers a secure way to produce random numbers: their unpredictability is intrinsic and can be certified just by observing the statistic of the measurement outcomes, without assumptions on how they are produced. To do…

Standard quantum information theory is founded on the assumption that multi-party state space possesses a tensor product structure. Anyons, as quasiparticles in two-dimensional systems, exhibit unique entanglement properties that differ…

Quantum Physics · Physics 2025-12-25 Cheng-Qian Xu , Wenhao Ye , Li You

We undertake experimental detection of the entanglement present in arbitrary three-qubit pure quantum states on an NMR quantum information processor. Measurements of only four observables suffice to experimentally differentiate between the…

Quantum Physics · Physics 2018-09-06 Amandeep Singh , Harpreet Singh , Kavita Dorai , Arvind

Strong quantum nonlocality was introduced recently as a stronger manifestation of nonlocality in multipartite systems through the notion of local irreducibility in all bipartitions. Known existence results for sets of strongly nonlocal…

Quantum Physics · Physics 2020-10-07 Fei Shi , Mengyao Hu , Lin Chen , Xiande Zhang

The hybrid entangled states generated, e.g., in a trapped-ion or atom-cavity system, have exactly one ebit of entanglement, but are not maximally entangled. We demonstrate this by showing that they violate, but in general do not maximally…

Quantum Physics · Physics 2009-11-07 Zeng-Bing Chen , Guang Hou , Yong-De Zhang

We relate the phenomenon of local indistinguishability of orthogonal states with the properties of unextendibility and uncompletability of entangled bases for bipartite and multipartite quantum systems. We prove that all two-qubit…

Quantum Physics · Physics 2023-04-18 Saronath Halder , Ujjwal Sen

A recent paper [L. Heaney, A. Cabello, M. F. Santos, and V. Vedral, New Journal of Physics, 13, 053054 (2011)] revealed that a single quantum symmetrically delocalized over N modes, namely a W state, effectively allows for…

Quantum Physics · Physics 2012-01-10 Amine Laghaout , Gunnar Björk , Ulrik L. Andersen

The nonlocal properties of the W states are investigated under particle loss. By removing all but two particles from an $N$-qubit W state, the resulting two-qubit state is still entangled. Hence, the W state has high persistency of…

Quantum Physics · Physics 2016-05-20 Péter Diviánszky , Réka Trencsényi , Erika Bene , Tamás Vértesi