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The usual derivation of the violation of Bell-type inequalities can be applied actually only for small distances between detectors. It does not take into account the dependence of the quantum mechanical wave function on space-time…

Quantum Physics · Physics 2023-12-13 Timofei Rusalev , Daniil Stepanenko , Igor Volovich

Many typical Bell experiments can be described as follows. A source repeatedly distributes particles among two spacelike separated observers. Each of them makes a measurement, using an observable randomly chosen out of several possible…

Quantum Physics · Physics 2015-01-08 Michael Epping , Hermann Kampermann , Dagmar Bruß

Tests such as Bell's inequality and Hardy's paradox show that joint probabilities and correlations between distant particles in quantum mechanics are inconsistent with local realistic theories. Here we experimentally demonstrate these…

In two-mode interferometry, for a given total photon number $N$, entangled Fock state superpositions of the form $(|N-m\rangle_a|m\rangle_b+e^{i (N-2m)\phi}|m\rangle_a|N-m\rangle_b)/\sqrt{2}$ have been considered for phase estimation.…

Bell-inequality violations establish that two systems share some quantum entanglement. We give a simple test to certify that two systems share an asymptotically large amount of entanglement, n EPR states. The test is efficient: unlike…

Quantum Physics · Physics 2018-09-06 Rui Chao , Ben W. Reichardt , Chris Sutherland , Thomas Vidick

We consider Bell experiments with N spatially separated qubits where loss is present and restrict to two measurement settings per site. We note the Mermin-Ardehali-Belinskii-Klyshko (MABK) Bell inequalities do not present a tight bound for…

Quantum Physics · Physics 2014-02-21 M. D. Reid

We propose a test of nonlocality for continuous variables using a two-mode squeezed state as the source of nonlocal correlations and a measurement scheme based on conditional homodyne detection. Both the CHSH- and the CH-inequality are…

Quantum Physics · Physics 2009-11-10 Hyunchul Nha , H. J. Carmichael

A common experimental strategy for demonstrating non-classical correlations is to show violation of a Bell inequality by measuring a continuously emitted stream of entangled photon pairs. The measurements involve the detection of photons by…

Quantum Physics · Physics 2015-03-11 Emanuel Knill , Scott Glancy , Sae Woo Nam , Kevin Coakley , Yanbao Zhang

We show that a recent observation by Yan leads to a method to experimentally test whether a higher-than-quantum violation of the Clauser-Horne-Shimony-Holt Bell inequality is possible (assuming that the sum of probabilities of pairwise…

Quantum Physics · Physics 2013-03-27 Adan Cabello

We show that arbitrary functions of continuous variables, e.g. position and momentum, can be used to generate tests that distinguish quantum theory from local hidden variable theories. By optimising these functions, we obtain more robust…

Quantum Physics · Physics 2009-11-16 Q. Y. He , E. G. Cavalcanti , M. D. Reid , P. D. Drummond

We show that the use of probabilistic noiseless amplification in entangled coherent state-based schemes for the test of quantum non locality provides substantial advantages. The threshold amplitude to falsify a Bell-CHSH non locality test,…

Quantum Physics · Physics 2013-05-14 G. Torlai , G. McKeown , P. Marek , R. Filip , H. Jeong , M. Paternostro , G. De Chiara

The decay of Higgs boson into two spin-1/2 particles provides an ideal system to reveal quantum entanglement and Bell-nonlocality. Future $e^+e^-$ colliders can improve the measurement accuracy of the spin correlation of tau lepton pairs…

High Energy Physics - Phenomenology · Physics 2024-07-10 Kai Ma , Tong Li

We construct a Bell inequality from the Clauser-Horne-Shimony-Holt inequality for two qubits that provides a stronger bound on the correlations of entangled states than allowed by the CHSH inequality. The argument involved here can be…

Quantum Physics · Physics 2007-11-07 Zeqian Chen

Any Bell test consists of a sequence of measurements on a quantum state in space-like separated regions. Thus, a state is better than others for a Bell test when, for the optimal measurements and the same number of trials, the probability…

Quantum Physics · Physics 2009-11-11 Antonio Acin , Richard Gill , Nicolas Gisin

Detection and quantification of entanglement in quantum resources are two key steps in the implementation of various quantum-information processing tasks. Here, we show that Bell-type inequalities are not only useful in verifying the…

Quantum Physics · Physics 2011-02-28 Yeong-Cherng Liang , Tamas Vertesi , Nicolas Brunner

We propose the use of entangled pairs of neutral kaons, considered as a promising tool to close the well known loopholes affecting generic Bell's inequality tests, in a specific Hardy-type experiment. Hardy's contradiction without…

Quantum Physics · Physics 2009-11-07 A. Bramon , G. Garbarino

Bell-type inequalities and violations thereof reveal the fundamental differences between standard probability theory and its quantum counterpart. In the course of previous investigations ultimate bounds on quantum mechanical violations have…

Quantum Physics · Physics 2007-05-23 Stefan Filipp , Karl Svozil

Two important ingredients necessary for obtaining Bell nonlocal correlations between two spatially separated parties are an entangled state shared between them and an incompatible set of measurements employed by each of them. We focus on…

Quantum Physics · Physics 2025-05-26 Priya Ghosh , Chirag Srivastava , Swati Choudhary , Ujjwal Sen

Bell's inequality fundamentally changed our understanding of quantum mechanics. Bell's insight that non-local correlations between quantum systems cannot be explained classically can be verified experimentally, and has numerous applications…

Quantum Physics · Physics 2015-06-22 Laura Mančinska , Stephanie Wehner

The Clauser-Horne-Shimony and Holt inequality applies when measurements with binary outcomes are performed on physical systems under the assumption of local realism. Testing such inequalities in the quantum realm usually involves either…

Quantum Physics · Physics 2015-04-28 A. Ketterer , A. Keller , T. Coudreau , P. Milman