Broad Feshbach resonance in the 6Li-40K mixture

TL;DR

This paper models and experimentally characterizes a broad Feshbach resonance in a 6Li-40K mixture, enabling studies of universal crossover physics in mass-imbalanced fermionic gases.

Contribution

It provides the first experimental measurement of a Feshbach resonance width in the 6Li-40K mixture and develops a model to predict resonance properties.

Findings

First experimental determination of resonance width in 6Li-40K

Model accurately predicts resonance positions and widths

Resonance width measured as Delta B=1.5(5) G

Abstract

We study the widths of interspecies Feshbach resonances in a mixture of the fermionic quantum gases 6Li and 40K. We develop a model to calculate the width and position of all available Feshbach resonances for a system. Using the model we select the optimal resonance to study the 6Li/40K mixture. Experimentally, we obtain the asymmetric Fano lineshape of the interspecies elastic cross section by measuring the distillation rate of 6Li atoms from a potassium-rich 6Li/40K mixture as a function of magnetic field. This provides us with the first experimental determination of the width of a resonance in this mixture, Delta B=1.5(5) G. Our results offer good perspectives for the observation of universal crossover physics using this mass-imbalanced fermionic mixture.