Feshbach resonances of large mass-imbalance Er-Li mixtures

TL;DR

This paper reports the experimental discovery of Feshbach resonances in Er-Li mixtures with large mass imbalance, demonstrating the potential for tunable interactions in ultracold quantum gases.

Contribution

First observation of Feshbach resonances in large mass-imbalance Er-Li mixtures, including identification of broad resonances suitable for quantum gas tuning.

Findings

Resonant interspecies loss features observed up to 680 G

Most resonances are sub-Gauss, some are several Gauss wide

Broad resonances enable tunable interactions in ultracold mixtures

Abstract

We report on the experimental observation of Feshbach resonances in large mass-imbalance mixtures of Erbium (Er) and Lithium (Li). All combinations between ${}^{168}$Er, ${}^{166}$Er and ${}^7$Li, ${}^6$Li are cooled to temperatures of a few microkelvin, partially by means of sympathetic cooling together with Ytterbium (Yb) as a third mixture component. The Er-Li inelastic interspecies collisional properties are studied for magnetic fields up to 680 G. In all cases resonant interspecies loss features, indicative of Feshbach resonances, have been observed. While most resonances have sub-Gauss widths, a few of them are broad and feature widths of several Gauss. Those broad resonances are a key to the realization of ultracold Er-Li quantum gas mixtures with tunable interactions.