Decoherence and dephasing in strongly driven colliding Bose-Einstein condensates

TL;DR

This study investigates decoherence and dephasing in strongly driven colliding Bose-Einstein condensates, revealing suppression of mean-field shifts and providing quantitative agreement with Gross-Pitaevskii simulations.

Contribution

It demonstrates suppression of mean-field shifts under strong excitation and quantifies decoherence rates consistent with theoretical predictions.

Findings

Suppression of mean-field shift in strong excitation regime

Observation of oscillations with reduced broadening

Decoherence rate matches local density calculations

Abstract

We report on a series of measurements of decoherence and wavepacket dephasing between two colliding, strongly coupled, identical Bose-Einstein condensates. We measure, in the strong excitation regime, a suppression of the mean-field shift, compared to the shift which is observed for a weak excitation. This suppression is explained by applying the Gross-Pitaevskii energy functional. By selectively counting only the non-decohered fraction in a time of flight image we observe oscillations for which both inhomogeneous and Doppler broadening are suppressed, in quantitative agreement with a full Gross-Pitaevskii equation simulation. If no post selection is used, the decoherence rate due to collisions can be extracted, and is in agreement with the local density average calculated rate.