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Quantum nonlocality is typically assigned to systems of two or more well separated particles, but nonlocality can also exist in systems consisting of just a single particle, when one considers the subsystems to be distant spatial field…

Quantum Physics · Physics 2015-03-13 Libby Heaney , Adan Cabello , Marcelo F. Santos , Vlatko Vedral

Gisin's theorem assures that for any pure bipartite entangled state, there is violation of Bell-CHSH inequality revealing its contradiction with local realistic model. Whether, similar result holds for three-qubit pure entangled states,…

Quantum Physics · Physics 2013-05-29 Sujit K. Choudhary , Sibasish Ghosh , Guruprasad Kar , Ramij Rahaman

Amplitude damping changes entangled pure states into usually less-entangled mixed states. We show, however, that even local amplitude damping of one or two qubits can result in mixed states more entangled than pure states if one compares…

Quantum Physics · Physics 2013-04-18 Bohdan Horst , Karol Bartkiewicz , Adam Miranowicz

We study the relations between quantum coherence and quantum nonlocality, genuine quantum entanglement and genuine quantum nonlocality. We show that the coherence of a qubit state can be converted to the nonlocality of two-qubit states via…

Quantum Physics · Physics 2019-09-04 Ya Xi , Tinggui Zhang , Zhujun Zheng , Xianqing Li-Jost , Shao-Ming Fei

Understanding the relation between the different forms of inseparability in quantum mechanics is a longstanding problem in the foundations of quantum theory and has implications for quantum information processing. Here we make progress in…

Quantum Physics · Physics 2013-04-09 Daniel Cavalcanti , Antonio Acin , Nicolas Brunner , Tamas Vertesi

The aim of this thesis is to investigate quantum entanglement and quantum nonlocality of bipartite finite-dimensional systems (bipartite qudits). Entanglement is one of the most fascinating non-classical features of quantum theory, and…

Quantum Physics · Physics 2009-07-09 Christoph Spengler

A quantum computing system is typically represented by a set of non-interacting (local) two-state systems - qubits. Many physical systems can naturally have more accessible states, both local and non-local. We show that the resulting…

Quantum Physics · Physics 2017-05-02 Dmitry Solenov

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

We introduce a version of the chained Bell inequality for an arbitrary number of measurement outcomes, and use it to give a simple proof that the maximally entangled state of two d dimensional quantum systems has no local component. That…

Quantum Physics · Physics 2011-04-08 Jonathan Barrett , Adrian Kent , Stefano Pironio

Nonlocality without entanglement(NLWE) is a nonlocal phenomenon that occurs in quantum state discrimination of multipartite separable states. In the discrimination of orthogonal separable states, the term NLWE is used when the quantum…

Quantum Physics · Physics 2021-09-07 Donghoon Ha , Jeong San Kim

A comprehensive treatment of the quantification of randomness certified device-independently by using the Hardy and Cabello-Liang-Li (CLL) nonlocality relations is provided in the two parties - two measurements per party - two outcomes per…

Quantum Physics · Physics 2023-05-19 Souradeep Sasmal , Ashutosh Rai , Sayan Gangopadhyay , Dipankar Home , Urbasi Sinha

We show that positivity of {\it every} partial transpose of $N$-partite quantum states implies new inequalities on Bell correlations which are stronger than standard Bell inequalities by a factor of $2^{(N-1)/2}$. A violation of the…

Quantum Physics · Physics 2009-11-13 Koji Nagata

A proof of Bell's theorem without inequalities valid for both inequivalent classes of three-qubit entangled states under local operations assisted by classical communication, namely Greenberger-Horne-Zeilinger (GHZ) and W, is described.…

Quantum Physics · Physics 2009-07-28 Adan Cabello

The quantum entanglement as one of very important resources has been widely used in quantum information processing. In this work, we present a new kind of genuine multipartite entanglement. It is derived from special geometric feature of…

Quantum Physics · Physics 2021-11-29 Ming-Xing Luo

It is generally believed that Bell's inequality holds for the case of entangled states, including two correlated particles or special states of a single particle. Here, we derive a single-particle Bell's inequality for two correlated spin…

Quantum Physics · Physics 2007-05-23 A. Shafiee , M. Golshani

We investigate the internal logic of a quantum computer with two qubits, in the two particular cases of non-entanglement (separable states) and maximal entanglement (Bell's states). To this aim, we consider an internal (reversible)…

Quantum Physics · Physics 2007-05-23 Giulia Battilotti , Paola Zizzi

It is shown that the ensemble $\{p (\alpha),|\alpha>|\alpha^*>\}$ where $p (\alpha)$ is a Gaussian distribution of finite variance and $| \alpha>$ is a coherent state can be better discriminated with an entangled measurement than with any…

Quantum Physics · Physics 2013-05-29 J. Niset , A. Acin , U. L. Andersen , N. J. Cerf , R. García-Patrón , M. Navascues , M. Sabuncu

Bell inequalities have traditionally been used to demonstrate that quantum theory is nonlocal, in the sense that there exist correlations generated from composite quantum states that cannot be explained by means of local hidden variables.…

Quantum nonlocality is a counterintuitive phenomenon that lies beyond the purview of causal influences. Recently, Bell inequalities have been generalized to the case of quantum inputs, leading to a powerful family of semi-quantum Bell…

Quantum Physics · Physics 2016-08-12 Charles Ci Wen Lim

Based on the relative entropy, we give a unified characterization of quantum correlations for nonlocality, steerability, discord and entanglement for any bipartite quantum states. For two-qubit states we show that the quantities obtained…

Quantum Physics · Physics 2017-04-14 Tinggui Zhang , Hong Yang , Xianqing Li-Jost , Shao-Ming Fei