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I point out a sign mistake in the GHZ variant of Bell's theorem, invalidating its claim that the premisses of the EPR argument are inconsistent for systems of more than two particles in entangled quantum states.

General Physics · Physics 2024-09-10 Joy Christian

The theorem developed by John Bell constituted the starting point of a revolution that translated a philosophical question about the nature of reality into the broad and intense field of research of the quantum information technologies. We…

Quantum Physics · Physics 2023-10-16 Antonio Mandarino , Giovanni Scala

High dimensional quantum entanglement and the advancements in their experimental realization provide a playground for fundamental research and eventually lead to quantum technological developments. The Horodecki criterion determines whether…

Quantum Physics · Physics 2025-04-29 Swapnil Bhowmick , Som Kanjilal , A. K. Pan , Souradeep Sasmal

Entanglement is an useful resource because some global operations cannot be locally implemented using classical communication. We prove a number of results about what is and is not locally possible. We focus on orthogonal states, which can…

Quantum Physics · Physics 2009-11-07 Jonathan Walgate , Lucien Hardy

We propose a directly measurable criterion for the entanglement of two qubits. We compare the criterion with other criteria, and we find that for pure states, and some mixed states, it coincides with the state's concurrency. The measure can…

Quantum Physics · Physics 2016-08-16 Hoshang Heydari , Gunnar Björk , Luis Sánchez-Soto

The hierarchy of nonlocality and entanglement in multipartite systems is one of the fundamental problems in quantum physics. We study this topic in three-qubit systems considering the entanglement classification of stochastic local…

Quantum Physics · Physics 2022-06-07 Dian Zhu , Gang-Gang He , Fu-Lin Zhang

In this paper we consider the description by a general Bell-type non-local hidden variable theory (NLHVT) of bipartite quantum states with two observables per sub-system. We derive Bell inequalities of the…

Quantum Physics · Physics 2024-04-19 Bryan J Dalton

We study local-realistic inequalities, Bell-type inequalities, for bipartite pure states of finite dimensional quantum systems -- qudits. There are a number of proposed Bell-type inequalities for such systems. Our interest is in relating…

Quantum Physics · Physics 2017-04-19 Chandan Datta , Pankaj Agrawal , Sujit K. Choudhary

We investigate the genuine multipartite nonlocality of three-mode Gaussian states of continuous variable systems. For pure states, we present a simplified procedure to obtain the maximum violation of the Svetlichny inequality based on…

Quantum Physics · Physics 2014-01-08 Gerardo Adesso , Samanta Piano

The correlations between two qubits belonging to a three-qubit system can violate the Clauser-Horne-Shimony-Holt-Bell inequality beyond Cirel'son's bound [A. Cabello, Phys. Rev. Lett. 88, 060403 (2002)]. We experimentally demonstrate such a…

Quantum Physics · Physics 2007-05-23 Yu-Ao Chen , Tao Yang , An-Ning Zhang , Zhi Zhao , Adan Cabello , Jian-Wei Pan

We introduce a new method of investigating qutrit nonclassicality by translating qutrit operators to symmetric two-qubit operators. We show that this procedure partially resolves the discrepancy between maximal qutrit entanglement and…

The familiar Greenberger-Horne-Zeilinger (GHZ) states can be rewritten by entangling the Bell states for two qubits with a state of the third qubit, which is dubbed entangled entanglement. We show that in this way we obtain all 8…

Quantum Physics · Physics 2015-10-06 Gabriele Uchida , Reinhold A. Bertlmann , Beatrix C. Hiesmayr

We study the relation between distillability of multipartite states and violation of Bell's inequality. We prove that there exist multipartite bound entangled states (i.e. non-separable, non-distillable states) that violate a multipartite…

Quantum Physics · Physics 2009-11-07 W. Dür

We consider mixed states of two qubits and show under which global unitary operations their entanglement is maximized. This leads to a class of states that is a generalization of the Bell states. Three measures of entanglement are…

Quantum Physics · Physics 2009-11-06 Frank Verstraete , Koenraad Audenaert , Tijl De Bie , Bart De Moor

A set of Bell inequalities classifying the quantum entanglement of four-qubit states is presented. These inequalities involve only two measurement settings per observer and can characterize fully separable, bi-separable and tri-separable…

Quantum Physics · Physics 2013-07-26 Hui Zhao , Xing-Hua Zhang , Shao-Ming Fei , Zhi-Xi Wang

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

We construct an important missing piece in the entanglement theory of pure three-qubit states, which is a polynomial measure of W-entanglement, working in parallel to the three-tangle, which is a polynomial measure of GHZ-entanglement, and…

Quantum Physics · Physics 2025-12-12 Szilárd Szalay

Recently, Fan \textit{et al.} [Mod. Phys. Lett. A 36, 2150223 (2021)], presented a generalized Clauser-Horne-Shimony-Holt (CHSH) inequality, to identify $N$-qubit Greenberger-Horne-Zeilinger (GHZ) states. They showed an interesting…

Quantum Physics · Physics 2022-06-09 Gang-Gang He , Xing-Yan Fan , Fu-Lin Zhang

While all bipartite pure entangled states are known to generate correlations violating a Bell inequality, and are therefore nonlocal, the quantitative relation between pure-state entanglement and nonlocality is poorly understood. In fact,…

Quantum Physics · Physics 2018-08-14 Victoria Lipinska , Florian Curchod , Alejandro Máttar , Antonio Acín

Multipartite quantum states may exhibit different types of quantum entanglement in that they cannot be converted into each other by local quantum operations only, and fully understanding mathematical structures of different types of…

Quantum Physics · Physics 2020-06-24 Lijinzhi Lin , Zhaohui Wei
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