Broad feshbach resonance in the Li6-K40 mixture

Abstract

We study the widths of interspecies Feshbach resonances in a mixture of the fermionic quantum gases Li6 and K40. 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 Li6/K40 mixture. Experimentally, we obtain the asymmetric Fano line shape of the interspecies elastic cross section by measuring the distillation rate of Li6 atoms from a potassium-rich Li6/K40 mixture as a function of magnetic field. This provides us with the first experimental determination of the width of a resonance in this mixture, ΔB=1.5(5)G. Our results offer good perspectives for the observation of universal crossover physics using this mass-imbalanced fermionic mixture. © 2010 The American Physical Society.