Dual-Species Bose-Einstein Condensate of $^{87}$Rb and $^{133}$Cs

TL;DR

This paper demonstrates the creation of a dual-species Bose-Einstein condensate of rubidium-87 and cesium-133 using sympathetic cooling, revealing phase separation due to strong interspecies repulsion.

Contribution

It introduces an efficient method for forming dual-species BECs of $^{87}$Rb and $^{133}$Cs with phase separation, and produces large single-species cesium condensates.

Findings

Dual-species BEC of $^{87}$Rb and $^{133}$Cs achieved.

Phase separation observed indicating immiscibility.

Single-species $^{133}$Cs condensates of up to $6\times10^{4}$ atoms created.

Abstract

We report the formation of a dual-species Bose-Einstein condensate of $^{87}$Rb and $^{133}$Cs in the same trapping potential. Our method exploits the efficient sympathetic cooling of $^{133}$Cs via elastic collisions with $^{87}$Rb, initially in a magnetic quadrupole trap and subsequently in a levitated optical trap. The two condensates each contain up to $2\times10^{4}$ atoms and exhibit a striking phase separation, revealing the mixture to be immiscible due to strong repulsive interspecies interactions. Sacrificing all the $^{87}$Rb during the cooling, we create single species $^{133}$Cs condensates of up to $6\times10^{4}$ atoms.