Observation of interspecies Li-Cs Feshbach resonances

TL;DR

This paper reports the discovery of nineteen interspecies Feshbach resonances in a Cs-Li ultracold mixture, enabling control over interactions and potential molecule formation, with implications for quantum simulation and many-body physics.

Contribution

The study provides the first detailed mapping and assignment of interspecies Feshbach resonances in a Cs-Li mixture using coupled-channels calculations, improving understanding of LiCs ground state potentials.

Findings

Nineteen Feshbach resonances observed in Cs-Li mixture.

Identification of s- and p-wave molecular channels.

Potential to create polar LiCs molecules and study polarons.

Abstract

We report on the observation of nineteen interspecies Feshbach resonances in an optically trapped ultracold Bose-Fermi mixture of ^{133}Cs and ^{6}Li in the two energetically lowest spin states. We assign the resonances to s- and p-wave molecular channels by a coupled-channels calculation, resulting in an accurate determination of LiCs ground state potentials. Fits of the resonance position based on the undressed Asymptotic Bound State model do not provide the same level of accuracy as the coupled-channels calculation. Several broad s-wave resonances provide prospects to create fermionic LiCs molecules with a large dipole moment via Feshbach association followed by stimulated Raman passage. Two of the s-wave resonances overlap with a zero crossing of the Cs scattering length which offers prospects for the investigation of polarons in an ultracold Li-Cs mixture.