Probing light forces on cold atoms by noise correlation spectroscopy

TL;DR

This paper demonstrates that noise correlation spectroscopy in cold rubidium vapor enhances sensitivity to weak light-induced forces on atoms, revealing effects not observable in mean field measurements.

Contribution

It introduces a new application of noise correlation spectroscopy to detect light forces on cold atoms, supported by a theoretical model matching experimental results.

Findings

Noise correlation spectroscopy detects weak light forces.

Effects are observable in correlations but not in mean fields.

Theoretical model agrees with experimental data.

Abstract

Enhanced sensitivity in electromagnetically induced transparency (EIT) can be obtained by the use of noise correlation spectroscopy between the fields involved in the process. Here, we investigate EIT in a cold ($< 1$ mK) rubidium vapor and demonstrate sensitivity to detect weak light-induced forces on the atoms. A theoretical model is developed and shows good agreement with our measurements, enabling the attribution of the observed effects to the coupling of the atomic states to their motion. The effects remain unnoticed on the measurement of the mean fields but are clearly manifest in their correlations.