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The violation of Bell's inequalities in Einstein-Podolsky-Rosen experiments has been demonstrated for photons and ions. In all experiments of this kind the relation between visibility, efficiency, and Bell violation is generally unknown. In…

Quantum Physics · Physics 2007-05-23 W. A. Hofer

We show that connections between a degree of incompatibility of pairs of observables and the strength of violations of Bell's inequality found in recent investigations can be extended to a general class of probabilistic physical models. It…

Quantum Physics · Physics 2014-02-28 Neil Stevens , Paul Busch

Violations of Bell inequalities have been an incontestable indicator of non-classicality since the seminal paper by John Bell. However, recent claims of Bell inequalities violations with classical light have cast some doubts on their…

Quantum Physics · Physics 2018-01-09 Marcin Markiewicz , Dagomir Kaszlikowski , Pawel Kurzynski , Antoni Wojcik

This paper analyzes effects of time-dependence in the Bell inequality. A generalized inequality is derived for the case when coincidence and non-coincidence [and hence whether or not a pair contributes to the actual data] is controlled by…

Quantum Physics · Physics 2022-03-16 Jan-Åke Larsson , Richard Gill

First a generalized Bell-inequality for different times and for different quasi-spin states is developed. We focus on special quasi-spin eigenstates and times. The inequality based on a local realistic theory is violated by the CP-violating…

High Energy Physics - Phenomenology · Physics 2016-09-06 B. C. Hiesmayr

Based on the Bell theorem, it has been believed that a theoretical computation of the Bell correlation requires explicit use of an entangled state. Such a physical superposition of light waves occurs in the downconverter sources used in…

Quantum Physics · Physics 2021-01-14 Louis Sica

We review and compare Bell-state measurement and quantum teleportation schemes using linear optics with three different types of resources, i.e., two-photon pairs, entangled coherent states and hybrid entangled states. Remarkably, perfect…

Quantum Physics · Physics 2015-11-13 Seung-Woo Lee , Hyunseok Jeong

We propose a scheme to test Bell's inequalities for an arbitrary number of measurement outcomes on entangled continuous variable states. The Bell correlation functions are expressible in terms of phase-space quasiprobability functions with…

Quantum Physics · Physics 2007-05-23 W. Son , C. Brukner , M. S. Kim

The assumptions required for the derivation of Bell inequalities are not usually satisfied for random fields in which there are any thermal or quantum fluctuations, in contrast to the general satisfaction of the assumptions for classical…

Other Condensed Matter · Physics 2007-05-23 Peter Morgan

Bell's inequalities can be understood in three different ways depending on whether the numbers featuring in the inequalities are interpreted as classical probabilities, classical conditional probabilities, or quantum probabilities. In the…

Quantum Physics · Physics 2020-04-30 Gábor Hofer-Szabó

Bell inequalities and nonlocality have been widely studied in one-dimensional quantum systems. As a kind of quantum correlation, it is expected that bipartite nonlocaity should be present in quantum systems, just as bipartite entanglement…

Quantum Physics · Physics 2015-06-16 Zhao-Yu Sun , Yu-Ying Wu , Hai-Lin Huang , Bo-Jun Chen , Bo Wang

We report on a Bell experiment with space-like separation assuming that the measurement time is related to gravity-induced state reduction. Two energy-time entangled photons are sent through optical fibers and directed into unbalanced…

Quantum Physics · Physics 2010-05-12 D. Salart , A. Baas , J. A. W. van Houwelingen , N. Gisin , H. Zbinden

We show that homodyne measurements can be used to demonstrate violations of Bell's inequality with Gaussian states, when the local rotations used for these types of tests are implemented using nonlinear unitary operations. We reveal that…

Quantum Physics · Physics 2009-11-13 M. Paternostro , H. Jeong , T. C. Ralph

Testing and verifying imperfect multi-qubit quantum devices are important as such noisy quantum devices are widely available today. Bell inequalities are known useful for testing and verifying the quality of the quantum devices from their…

Quantum Physics · Physics 2025-05-16 Bo Yang , Rudy Raymond , Hiroshi Imai , Hyungseok Chang , Hidefumi Hiraishi

Bell inequalities for number measurements are derived via the observation that the bits of the number indexing a number state are proper qubits. Violations of these inequalities are obtained from the output state of the nondegenerate…

Quantum Physics · Physics 2022-03-16 Jan-Åke Larsson

Recently, Liu et al. [Commun. Theor. Phys. 57, 583, 2012] proposed a quantum private comparison protocol based on entanglement swapping of Bell states, which aims to securely compare the equality of two participants' information with the…

Quantum Physics · Physics 2024-04-30 Wen-Jie Liu , Chao Liu , Yu Zheng , Zheng-Fei Chen

For a system composed of two particles Bell's theorem asserts that averages of physical quantities determined from local variables must conform to a family of inequalities. In this work we show that a classical model containing a local…

Quantum Physics · Physics 2008-06-22 A. Matzkin

A certain class of parametric down-conversion Bell type experiments has the following features. In the idealized perfect situation it is in only 50% of cases that each observer receives a photon; in the other 50% of cases one observer…

Quantum Physics · Physics 2009-10-30 Sandu Popescu , Lucien Hardy , Marek Zukowski

We consider the entanglement of orthogonal generalized Bernoulli states in two separate single-mode high-$Q$ cavities. The expectation values and the correlations of the electric field in the cavities are obtained. We then define, in each…

Quantum Physics · Physics 2009-11-11 R. Lo Franco , G. Compagno , A. Messina , A. Napoli

The connection between quantum optical nonclassicality and the violation of Bell's inequalities is explored. Bell type inequalities for the electromagnetic field are formulated for general states of quantised radiation and their violation…

Quantum Physics · Physics 2009-10-31 Arvind , N. Mukunda