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Last years, bounds on the maximal quantum violation of general Bell inequalities were intensively discussed in the literature via different mathematical tools. In the present paper, we analyze quantum violation of general Bell inequalities…

Quantum Physics · Physics 2019-11-19 Elena R. Loubenets

Violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality certifies genuine quantum correlations. In this work, we formalize in Lean 4 the rigidity theorem -- any strategy achieving near-optimal CHSH value must be locally isometric to…

Quantum Physics · Physics 2026-04-07 Tianrun Zhao , Nengkun Yu

In the analysis of experiments designed to reveal violation of Bell-type inequalities, it is usually assumed that any hidden variables associated with the nth particle pair would be independent of measurement choices and outcomes for the…

Quantum Physics · Physics 2009-11-07 Jonathan Barrett , Daniel Collins , Lucien Hardy , Adrian Kent , Sandu Popescu

We in this Letter derive analytic formulas of Bell correlations in terms of quantum probability statistics under the assumption of measuring outcome-independence. For a spin-1/2 singlet state we find analytically that the violations of…

Quantum Physics · Physics 2013-04-09 Zhigang Song , J. -Q. Liang , L. -F. Wei

Bell inequalities provide a fundamental tool for probing nonlocal correlations, yet their quantum bound, that is, the maximal value attainable through quantum strategies, is rarely accessible analytically. In this work, we introduce a…

Quantum Physics · Physics 2025-11-25 Patryk Michalski , Arturo Konderak , Wojciech Bruzda , Remigiusz Augusiak

In the present paper it is demonstrated that the quantum correlation (2-dim unitary parameter vectors) can be arbitrarily close approximated with a local hidden variables model. Moreover, the CHSH inequality can be violated with the present…

General Physics · Physics 2008-11-28 J. F. Geurdes

This work establishes computable bounds between f-divergences for probability measures within a generalized quasi-$\varepsilon_{(M,m)}$-neighborhood framework. We make the following key contributions. (1) a unified characterization of local…

Information Theory · Computer Science 2025-08-12 Xinchun Yu , Shuangqing Wei , Xiao-Ping Zhang

By establishing CHSH operators and CHSH-type inequalities, we show that any entangled pure state in infinite-dimensional systems is entangled in a $2\otimes2$ subspace. We find that, for infinite-dimensional systems, the corresponding…

Quantum Physics · Physics 2013-08-16 Yu Guo

We computationally investigate the complete polytope of Bell inequalities for 2 particles with small numbers of possible measurements and outcomes. Our approach is limited by Pitowsky's connection of this problem to the computationally hard…

Quantum Physics · Physics 2023-03-23 Daniel Collins , Nicolas Gisin

Quantum-enhanced measurements use quantum mechanical effects in order to enhance the sensitivity of the measurement of classical quantities, such as the length of an optical cavity. The major goal is to beat the standard quantum limit…

Quantum Physics · Physics 2011-03-10 Daniel Braun , John Martin

To reproduce in a local hidden variables theory correlations that violate Bell inequalities, communication must occur between the parties. We show that the amount of violation of a Bell inequality imposes a lower bound on the average…

Quantum Physics · Physics 2007-10-22 Stefano Pironio

We consider quantum ensembles which are determined by pre- and post-selection. Unlike the case of only pre-selected ensembles, we show that in this case the probabilities for measurement outcomes at intermediate times satisfy causality only…

Quantum Physics · Physics 2009-11-13 S. Marcovitch , B. Reznik , L. Vaidman

Elegant Bell inequality is well known for its distinctive property, being maximally violated by maximal entanglement, mutually unbiased bases, and symmetric informationally complete positive operator-valued measure elements. Despite its…

Quantum Physics · Physics 2026-02-17 Kwangil Bae , Junghee Ryu , Ilkwon Sohn , Wonhyuk Lee

Optical hybrid entanglement can be created between two qubits, one encoded in a single photon and another one in coherent states with opposite phases. It opens the path to a variety of quantum technologies, such as heterogeneous quantum…

In the derivation of local bound of a Bell's inequality, the response functions corresponding to the different outcomes of measurements are fixed by the relevant hidden variables irrespective of the fact if the measurement is unsharp. In…

Quantum Physics · Physics 2018-06-05 Asmita Kumari , A. K. Pan

In this paper we consider one parameter generalizations of some non - symmetric divergence measures. Measures are \textit{relative information}, $\chi ^2 - $\textit{divergence}, \textit{relative J-divergence}, \textit{relative…

Statistics Theory · Mathematics 2007-06-13 Inder Jeet Taneja , Pranesh Kumar

The growing recognition that entanglement is not exclusively a quantum property, and does not even originate with Schr\"odinger's famous remark about it [Proc. Camb. Phil. Soc. 31, 555 (1935)], prompts examination of its role in marking the…

Quantum Physics · Physics 2015-06-29 Xiao-Feng Qian , Bethany Little , John C. Howell , J. H. Eberly

We consider violation of CHSH inequality for states before and after entanglement swapping. We present a pair of initial states which do not violate CHSH inequality however the final state violates CHSH inequality for some results of Bell…

Quantum Physics · Physics 2010-11-01 Antoni Wojcik , Joanna Modlawska , Andrzej Grudka , Mikolaj Czechlewski

To date, most efforts to demonstrate quantum nonlocality have concentrated on systems of two (or very few) particles. It is however difficult in many experiments to address individual particles, making it hard to highlight the presence of…

We introduce Bell inequalities based on covariance, one of the most common measures of correlation. Explicit examples are discussed, and violations in quantum theory are demonstrated. A crucial feature of these covariance Bell inequalities…

Quantum Physics · Physics 2017-12-27 Victor Pozsgay , Flavien Hirsch , Cyril Branciard , Nicolas Brunner
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