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An ensemble of product states is said to exhibit "quantum nonlocality without entanglement" if the states cannot be optimally discriminated by local operations and classical communication (LOCC). We show that this property can depend on the…

Quantum Physics · Physics 2025-06-26 Shayeef Murshid , Tathagata Gupta , Vincent Russo , Somshubhro Bandyopadhyay

We strengthen the bound on the correlations of two spin-1/2 particles (qubits) in separable (non-entangled) states for locally orthogonal spin directions by much tighter bounds than the well-known Bell inequality. This provides a sharper…

Quantum Physics · Physics 2008-02-22 J. Uffink , M. Seevinck

In this paper we extend the ladder proof of nonlocality without inequalities for two spin-half particles given by Boschi et al [PRL 79, 2755 (1997)] to the case in which the measurement settings of the apparatus measuring one of the…

Quantum Physics · Physics 2009-11-07 Jose L. Cereceda

Quantum theory predicts the existence of genuinely tripartite-entangled states, which cannot be obtained from local operations over any bipartite entangled states and unlimited shared randomness. Some of us recently proved that this feature…

Quantum theory allows for nonlocality without entanglement. Notably, there exist bipartite quantum measurements consisting of only product eigenstates, yet they cannot be implemented via local quantum operations and classical communication.…

Quantum Physics · Physics 2023-07-12 Ivan Šupić , Nicolas Brunner

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

Nonlocality can be studied through different approaches, such as Bell's inequalities, and it can be found in numerous quantum states, including GHZ states or graph states. Hardy's paradox, or Hardy-type nonlocality, provides a way to…

Quantum Physics · Physics 2026-01-09 Duc Manh Doan , Hung Q. Nguyen

According to quantum theory, the outcomes obtained by measuring an entangled state necessarily exhibit some randomness if they violate a Bell inequality. In particular, a maximal violation of the CHSH inequality guarantees that 1.23 bits of…

Quantum Physics · Physics 2012-03-23 Antonio Acin , Serge Massar , Stefano Pironio

In a recent article [Phys. Rev. A 54, 1793 (1996)] Krenn and Zeilinger investigated the conditional two-particle correlations for the subensemble of data obtained by selecting the results of the spin measurements by two observers 1 and 2…

Quantum Physics · Physics 2008-12-18 Jose L. Cereceda

The unique entanglement measure is concurrence in a 2-qubit pure state. The maximum violation of Bell's inequality is monotonically increasing for this quantity. Therefore, people expect that pure state entanglement is relevant to the…

Quantum Physics · Physics 2022-12-14 Xingyu Guo , Chen-Te Ma

Kar's recent proof showing that a maximally entangled state of two spin-1/2 particles gives the largest violation of a Bell inequality is extended to N spin-1/2 particles (with N greater than or equal to 3). In particular, it is shown that…

Quantum Physics · Physics 2009-10-31 Jose L. Cereceda

Quantum nonlocality is presented often as the most remarkable and inexplicable phenomenon known to modern science which was confirmed in the experiments proving the violation of Bell Inequalities (BI). It has been known already for a long…

Quantum Physics · Physics 2021-06-09 Marian Kupczynski

Nonlocality and quantum entanglement constitute two special aspects of the quantum correlations existing in quantum systems, which are of paramount importance in quantum-information theory. Traditionally, they have been regarded as…

Quantum Physics · Physics 2015-05-27 J. Batle , M. Casas

EPR paper contains an error. Its correction leads to a conclusion that position and momentum of a particle can be defined precisely simultaneously, EPR paradox does not exist and uncertainty relations have nothing to do with quantum…

General Physics · Physics 2010-09-13 V. K. Igatovich

We provide an explicit example of a Bell inequality with 3 settings and 2 outcomes per site for which the largest violation is not obtained by the maximally entangled state, even if its dimension is allowed to be arbitrarily large. This…

Quantum Physics · Physics 2013-05-29 Thomas Vidick , Stephanie Wehner

We demonstrate genuine three-mode nonlocality based on phase space formalism. A Svetlichny-type Bell inequality is formulated in terms of the $s$-parameterized quasiprobability function. We test such tool using exemplary forms of three-mode…

Quantum Physics · Physics 2015-06-12 Seung-Woo Lee , Mauro Paternostro , Jinhyoung Lee , Hyunseok Jeong

The exploration of entanglement and Bell non-locality among multi-particle quantum systems offers a profound avenue for testing and understanding the limits of quantum mechanics and local real hidden variable theories. In this work, we…

Quantum Physics · Physics 2025-10-23 Paweł Horodecki , Kazuki Sakurai , Abhyoudai S. Shaleena , Michael Spannowsky

Generic forms of the entangled states of two spin-1 (and spin-3/2) particles, along with the set of appropriate spin observables that together exhibit maximum nonlocality under the Hardy's nonlocality test are given; the maximum nonlocality…

Quantum Physics · Physics 2015-08-25 Kaushik P. Seshadreesan , Sibasish Ghosh

Quantum entanglement plays a central role in many areas of physics, from quantum information science to many-body systems. In order to grasp the essence of this phenomenon, it is fundamental to understand how different manifestations of…

Quantum Physics · Physics 2014-11-11 Tamas Vértesi , Nicolas Brunner

Quantum nonlocality is tested for an entangled coherent state, interacting with a dissipative environment. A pure entangled coherent state violates Bell's inequality regardless of its coherent amplitude. The higher the initial nonlocality,…

Quantum Physics · Physics 2009-11-07 D. Wilson , H. Jeong , M. S. Kim