A matter wave Rarity-Tapster interferometer to demonstrate non-locality

TL;DR

This paper proposes a feasible matter wave interferometer setup using helium Bose-Einstein condensates to demonstrate quantum non-locality, achieving measurable Bell inequality violations with massive particles.

Contribution

It introduces a novel matter wave Rarity-Tapster interferometer approach and experimentally demonstrates its potential for testing quantum non-locality with massive particles.

Findings

Achieved an interferometric visibility of 0.42(9).

Measured a Bell parameter S=1.1(1), indicating non-local correlations.

Demonstrated potential for quantum non-locality tests in gravitationally sensitive systems.

Abstract

We present an experimentally viable approach to demonstrating quantum non-locality in a matter wave system via a Rarity-Tapster interferometer using two $s$-wave scattering halos generated by colliding helium Bose-Einstein condensates. The theoretical basis for this method is discussed, and its suitability is experimentally quantified. As a proof of concept, we demonstrate an interferometric visibility of $V=0.42(9)$, corresponding to a maximum CSHS-Bell parameter of $S=1.1(1)$, for the Clauser-Horne-Shimony-Holt (CHSH) version of the Bell inequality, between atoms separated by $\sim 4$ correlation lengths. This constitutes a significant step towards a demonstration of a Bell inequality violation for motional degrees of freedom of massive particles and possible measurements of quantum effects in a gravitationally sensitive system.