Control of Interaction-Induced Dephasing of Bloch Oscillations

TL;DR

This paper demonstrates control over interaction-induced dephasing in Bloch oscillations of a Bose-Einstein condensate by tuning interactions via a Feshbach resonance, enabling precise interferometry and observation of quantum phenomena.

Contribution

It introduces a method to significantly extend dephasing times in Bloch oscillations by tuning atomic interactions to zero, enhancing quantum control in optical lattices.

Findings

Dephasing time increased from a few to over twenty thousand oscillation periods.

Minimizing dephasing enables BEC-based atom interferometry in the non-interacting limit.

Observation of collapse and revivals of Bloch oscillations under a spatial force gradient.

Abstract

We report on the control of interaction-induced dephasing of Bloch oscillations for an atomic Bose-Einstein condensate in an optical lattice under the influence of gravity. When tuning the strength of the interaction towards zero by means of a Feshbach resonance, the dephasing time is increased from a few to more than twenty thousand Bloch oscillation periods. We quantify the dephasing in terms of the width of the quasi-momentum distribution and measure its dependence on time for different values of the scattering length. Minimizing the dephasing allows us to realize a BEC-based atom interferometer in the non-interacting limit. We use it for a precise determination of a zero-crossing for the atomic scattering length and to observe collapse and revivals of Bloch oscillations when the atomic sample is subject to a spatial force gradient.