Spin self-rephasing and very long coherence times in a trapped atomic ensemble

TL;DR

This paper demonstrates unexpectedly long coherence times in ultra-cold trapped 87Rb atoms due to a spin self-rephasing mechanism, supported by a theoretical model and experimental evidence, revealing a general synchronization effect.

Contribution

The study uncovers a spin self-rephasing mechanism in ultra-cold atoms, explaining coherence times far exceeding initial expectations and providing a theoretical framework for this phenomenon.

Findings

Observed coherence times of 58 seconds versus expected 3 seconds

Identified spin self-rephasing as the cause of extended coherence

Developed a theory matching experimental results

Abstract

We perform Ramsey spectroscopy on the ground state of ultra-cold 87Rb atoms magnetically trapped on a chip in the Knudsen regime. Field inhomogeneities over the sample should limit the 1/e contrast decay time to about 3 s, while decay times of 58 s are actually observed. We explain this surprising result by a spin self-rephasing mechanism induced by the identical spin rotation effect originating from particle indistinguishability. We propose a theory of this synchronization mechanism and obtain good agreement with the experimental observations. The effect is general and susceptible to appear in other physical systems.