Measurement of spectral functions of ultracold atoms in disordered potentials

TL;DR

This paper measures the spectral functions of ultracold atoms in 3D disordered potentials, revealing a crossover from quantum to classical regimes and enabling new studies of Anderson localization.

Contribution

It introduces a novel experimental method to measure spectral functions in disordered ultracold atoms, bridging quantum and classical regimes.

Findings

Spectral functions vary with disorder strength over two orders of magnitude.

Excellent agreement between experimental results and numerical simulations.

Method enables detailed exploration of Anderson localization in three dimensions.

Abstract

We report on the measurement of the spectral functions of noninteracting ultracold atoms in a three-dimensional disordered potential resulting from an optical speckle field. Varying the disorder strength by 2 orders of magnitude, we observe the crossover from the "quantum" perturbative regime of low disorder to the "classical" regime at higher disorder strength, and find an excellent agreement with numerical simulations. The method relies on the use of state-dependent disorder and the controlled transfer of atoms to create well-defined energy states. This opens new avenues for experimental investigations of three-dimensional Anderson localization.