Coherent Backscattering of Ultracold Atoms

TL;DR

This paper reports the direct observation of coherent backscattering of ultracold atoms in a disordered potential, demonstrating quantum coherence effects and providing insights into microscopic transport properties.

Contribution

It presents the first direct observation of CBS in ultracold atoms in a quasi-2D setup, linking coherence phenomena to quantum transport in disordered media.

Findings

Observation of CBS peak in ultracold atoms

Agreement of CBS evolution with theoretical predictions

Determination of microscopic transport quantities

Abstract

We report on the direct observation of coherent backscattering (CBS) of ultracold atoms, in a quasi-two-dimensional configuration. Launching atoms with a well-defined momentum in a laser speckle disordered potential, we follow the progressive build up of the momentum scattering pattern, consisting of a ring associated with multiple elastic scattering, and the CBS peak in the backward direction. Monitoring the depletion of the initial momentum component and the formation of the angular ring profile allows us to determine microscopic transport quantities. The time resolved evolution of the CBS peak is studied and is found a fair agreement with predictions, at long times as well as at short times. The observation of CBS can be considered a direct signature of coherence in quantum transport of particles in disordered media. It is responsible for the so called weak localization phenomenon, which is the precursor of Anderson localization.