Two-dimensional electronic spectroscopy of an ultracold gas

TL;DR

This paper demonstrates femtosecond multidimensional spectroscopy on ultracold $^7$Li gases, revealing interparticle interactions and enabling detailed studies of many-body effects with high frequency and time resolution.

Contribution

It introduces a phase modulation spectroscopy setup for ultracold gases, enabling observation of double quantum coherence responses in a cold atomic sample.

Findings

Observation of double quantum coherence response indicating interparticle interactions

High frequency resolution of 3 GHz and potential 200 fs time resolution

Paves the way for detailed many-body effect investigations in ultracold gases

Abstract

Femtosecond coherent multidimensional spectroscopy is demonstrated for an ultracold gas. For this, a setup for phase modulation spectroscopy is used to probe the $3^2\mathrm{S}_{1/2} - 2^2\mathrm{P}_{1/2, 3/2}$ transition in an 800 $\mu$K-cold sample of $^7$Li atoms confined in a magneto-optical trap. The observation of a double quantum coherence response, a signature of interparticle interactions, paves the way for detailed investigations of few- and many-body effects in ultracold atomic and molecular gases using this technique. The experiment combines a frequency resolution of 3 GHz with a potential time resolution of 200 fs, which allows for high-resolution studies of ultracold atoms and molecules both in the frequency and in the time domain.