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New Bell inequalities for the singlet state: Going beyond the Grothendieck bound

2007/02/28 by Itamar Pitowsky · 2 citations
Computer Science · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #quant-ph

paper · pdf · doi:10.1063/1.2826227

published as Journal of Mathematical Physics 49, 012101 (2008) · 18 pages, two figures, some corrections and additional references, published version

openalex publication_date 2008/01/01 · arxiv created 2008/02/05 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28

Abstract

Contemporary versions of Bell’s argument [Physics (Long Island City, N.Y.) 1, 195 (1964)] against local hidden variable (LHV) theories are based on the Clauser-Horne-Shimony-Holt (CHSH) [Phys. Rev. Lett. 23, 880 (1969)] inequality and various attempts to generalize it. The amount of violation of these inequalities cannot exceed the bound set by the Grothendieck constants. However, if we go back to the original derivation by Bell and use the perfect anticorrelation embodied in the singlet spin state, we can go beyond these bounds. In this paper, we derive two-particle Bell inequalities for traceless two-outcome observables, whose violation in the singlet spin state go beyond the Grothendieck constants both for the two and three dimensional cases. Moreover, creating a higher dimensional analog of perfect correlations and applying a recent result of Alon et al. [Invent. Math. 163, 499 (2006)], we prove that there are two-particle Bell inequalities for traceless two-outcome observables whose violation increases to infinity as the dimension and number of measurements grow. Technically, these result are possible because perfect correlations (or anticorrelations) allow us to transport the indices of the inequality from the edges of a bipartite graph to those of the complete graph. Finally, it is shown how to apply these results to mixed Werner states, provided that the noise does not exceed 20%.

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