Competition between Spin Echo and Spin Self-Rephasing in a Trapped Atom Interferometer
Résumé
We perform Ramsey interferometry on an ultracold 87Rb ensemble confined in an optical dipole
trap. We use a \pi-pulse set at the middle of the interferometer to restore the coherence of the spin
ensemble 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 dephasing
of the spin ensemble leading to a faster contrast decay of the interferometer. We understand this
phenomenon as a competition between the spin-echo technique and an exchange-interaction driven
spin self-rephasing mechanism based on the identical spin rotation effect. Our experimental data is
well reproduced by a numerical model.
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