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arXiv · 1811.05681

A strong Bell correlation witness between spatially separated pairs of atoms

D. K. Shin·B. M. Henson·S. S. Hodgman·T. Wasak·J. Chwedenczuk·A. G. Truscott
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Abstract

The violation of a Bell inequality is a striking demonstration of how quantum mechanics contradicts local realism. Although the original argument was presented with a pair of spin 1/2 particles, so far Bell inequalities have been shown to be violated using entangled pairs of photons, with recent measurements closing all possible loopholes in such a scheme. Equivalent demonstrations using massive particles have proven to be much more challenging, generally relying on post-selection of data or measuring an entanglement witness that relies on quantum mechanics. Here, we use a collision between two Bose-Einstein condensates to generate the momentum-spin entangled pairs of ultracold helium atoms. We show that a maximally entangled Bell triplet state results and report a direct observation of a strong Bell correlation witness. Based on the high degree of entanglement and the controllability of ultracold atomic systems, extensions to this scheme would allow a demonstration of nonlocality with massive entangled pairs, following the original idea of Bell. Other applications include the demonstration of the Einstein-Podolsky-Rosen paradox, quantum metrology and tests of phenomena from exotic theories sensitive to such systems including gravitational decoherence and quantum gravity.

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D. K. Shin, B. M. Henson, S. S. Hodgman, T. Wasak, J. Chwedenczuk, A. G. Truscott. 2018-11-23. A strong Bell correlation witness between spatially separated pairs of atoms. https://doi.org/10.1038/s41467-019-12192-8

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