Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding

TL;DR

This paper introduces superfluid shielding, a technique that extends the coherence time of separated Bose-Einstein condensates beyond the shot-noise limit by immersing them in a superfluid bath, reducing inhomogeneous dephasing effects.

Contribution

The authors demonstrate a novel superfluid shielding method that cancels inhomogeneous potentials, significantly enhancing coherence times of Bose-Einstein condensates beyond the projection noise limit.

Findings

Coherence times surpass the shot-noise limit using superfluid shielding.

Immersion in a superfluid bath reduces inhomogeneous dephasing.

Enhanced coherence improves quantum device performance.

Abstract

We demonstrate a new way to extend the coherence time of separated Bose-Einstein condensates that involves immersion into a superfluid bath. When both the system and the bath have similar scattering lengths, immersion in a superfluid bath cancels out inhomogeneous potentials either imposed by external fields or inherent in density fluctuations due to atomic shot noise. This effect, which we call superfluid shielding, allows for coherence lifetimes beyond the projection noise limit. We probe the coherence between separated condensates in different sites of an optical lattice by monitoring the contrast and decay of Bloch oscillations. Our technique demonstrates a new way that interactions can improve the performance of quantum devices.