Ultracold Cs$_2$ Feshbach Spectroscopy

TL;DR

This paper reports the observation of over 60 Feshbach resonances in ultracold cesium collisions, refining interaction potentials and providing detailed molecular state information relevant for Bose-Einstein condensation.

Contribution

It significantly improves the accuracy of cesium atom interaction potentials and elucidates the quantum structure of molecular states near dissociation.

Findings

Over 60 Feshbach resonances identified

Interaction potentials refined with better than 0.5% accuracy

Predicted collision properties for BEC experiments

Abstract

We have observed and located more than 60 magnetic field-induced Feshbach resonances in ultracold collisions of ground-state $^{133}$Cs atoms. These resonances are associated with molecular states with up to four units of rotational angular momentum, and are detected through variations in the elastic, inelastic, and radiative collision cross sections. These observations allow us to greatly improve upon the interaction potentials between two cesium atoms and to reproduce the positions of most resonances to accuracies better than 0.5%. Based on the relevant coupling scheme between the electron spin, nuclear spin, and orbital angular momenta of the nuclei, quantum numbers and energy structure of the molecular states beneath the dissociation continuum are revealed. Finally, we predict the relevant collision properties for cesium Bose-Einstein condensation experiments.