Spatial separation in a thermal mixture of ultracold $^{174}$Yb and $^{87}$Rb atoms

TL;DR

This study demonstrates that strong interactions in a thermal mixture of ultracold $^{174}$Yb and $^{87}$Rb atoms lead to notable spatial separation, driven by large interspecies interactions and three-body recombination, modeled successfully by diffusion equations.

Contribution

First observation of interaction-driven spatial separation in a thermal ultracold mixture of $^{174}$Yb and $^{87}$Rb atoms with a developed diffusion model.

Findings

Significant spatial separation observed between Yb and Rb atoms.

Large interspecies interaction strength and three-body recombination rates inferred.

Diffusion model successfully reproduces the experimental observations.

Abstract

We report on the observation of unusually strong interactions in a thermal mixture of ultracold atoms which cause a significant modification of the spatial distribution. A mixture of $^{87}$Rb and $^{174}$Yb with a temperature of a few $\mu$K is prepared in a hybrid trap consisting of a bichromatic optical potential superimposed on a magnetic trap. For suitable trap parameters and temperatures, a spatial separation of the two species is observed. We infer that the separation is driven by a large interaction strength between $^{174}$Yb and $^{87}$Rb accompanied by a large three-body recombination rate. Based on this assumption we have developed a diffusion model which reproduces our observations.