Spin correlations of strongly interacting massive fermion pairs as a test of Bell's inequality

Yoshiteru Sato

Publisher's note: Spin correlations of strongly interacting massive fermion Pairs as a test of bell's inequality, Publisher's note: Spin correlations of strongly interacting massive fermion Pairs as a test of bell's inequality

Robert A. Close

Hideyuki SAKAI, T. Saito, T. Ikeda +13 more

We report the results of the first-time test of the local hidden variable theories (Bell-Clauser-Horne-Shimony-Holt) involving strongly interacting pairs of massive spin $1/2$ hadrons from the decay of short-lived ($\ensuremath{\tau}<{10}^{\ensuremath{-}21}\mathrm{sec}$) $^{2}\mathrm{He}$ spin-singlet state, populated in the nuclear reaction $^{2}\mathrm{H}+^{1}\mathrm{H}\ensuremath{\rightarrow}^{2}\mathrm{He}+n$. The novel features of this experiment are (a) the use of an ``event-ready'' detector of nearly 100% efficiency to prepare an unbiased sample and (b) a focal-plane polarimeter of full $2\ensuremath{\pi}\text{ }\text{ }\mathrm{sr}$ acceptance with a random ``post selection'' of the reference axes. The spin-correlation function is deduced to be ${S}_{\mathrm{exp}}(\ensuremath{\pi}/4)=2.83\ifmmode\pm\else\textpm\fi{}{0.24}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.07}_{\mathrm{sys}}$. This result is in agreement with nonlocal quantum mechanical prediction and it violates the Bell-CHSH inequality of $|S|\ensuremath{\le}2$ at a confidence level of 99.3%.

V.L. Lyboshitz, M.I. Podgoretsky

Hideyuki SAKAI, Tôru Saitô, T. Ikeda +13 more

Received 19 October 2006DOI:https://doi.org/10.1103/PhysRevLett.97.179901©2006 American Physical Society

Tomasz Wasak, Jan Chwedeńczuk

We propose an experiment, where the Bell inequality is violated in a many-body system of massive particles. The source of correlated atoms is a spinor F=1 Bose-Einstein condensate residing in an optical lattice. We characterize the complete procedure-the local operations, the measurements, and the inequality-necessary to run the Bell test. We show how the degree of violation of the Bell inequality depends on the strengths of the two-body correlations and on the number of scattered pairs. We show that the system can be used to demonstrate the Einstein-Podolsky-Rosen paradox. Also, the scattered pairs are an excellent many-body resource for the quantum-enhanced metrology. Our results apply to any multimode system where the spin-changing collision drives the scattering into separate regions. The presented inquiry shows that such a system is versatile as it can be used for the tests of nonlocality, quantum metrology, and quantum information.