Competition between Spin Echo and Spin Self-Rephasing in a Trapped Atom Interferometer

TL;DR

This study investigates the interplay between spin echo and spin self-rephasing in a trapped ultracold atom interferometer, revealing how atomic density influences coherence preservation through competing mechanisms.

Contribution

It demonstrates the competition between spin echo and spin self-rephasing in a trapped atom system, supported by experimental data and numerical modeling.

Findings

High atomic density accelerates dephasing despite spin echo.

Spin self-rephasing can counteract or enhance spin echo effects.

Numerical models accurately reproduce experimental observations.

Abstract

We perform Ramsey interferometry on an ultracold 87Rb ensemble confined in an optical dipoletrap. We use a \pi-pulse set at the middle of the interferometer to restore the coherence of the spinensemble by canceling out phase inhomogeneities and creating a spin echo in the contrast. However,for high atomic densities, we observe the opposite behavior: the \pi-pulse accelerates the dephasingof the spin ensemble leading to a faster contrast decay of the interferometer. We understand thisphenomenon as a competition between the spin-echo technique and an exchange-interaction drivenspin self-rephasing mechanism based on the identical spin rotation effect. Our experimental data iswell reproduced by a numerical model.