Quantum degenerate mixtures of strontium and rubidium atoms

Quantum degenerate mixtures of strontium and rubidium atoms

We report on the realization of quantum degenerate gas mixtures of the alkaline-earth element strontium with the alkali element rubidium. A key ingredient of our scheme is sympathetic cooling of Rb by Sr atoms that are continuously laser cooled on a narrow linewidth transition. This versatile technique allows us to produce ultracold gas mixtures with a phase-space density of up to 0.06 for both elements. By further evaporative cooling we create double Bose-Einstein condensates of ⁸⁷Rb with either ⁸⁸Sr or ⁸⁴Sr, reaching more than 10⁵ condensed atoms per element for the ⁸⁴Sr-⁸⁷Rb mixture. These quantum gas mixtures constitute an important step towards the production of a quantum gas of polar, open-shell RbSr molecules.

Momentum distribution of Rb during sympathetic narrow-line laser cooling of Rb by Sr. The Rb phase-space density ρ is increased by a factor of more than 200 in 400ms.

Time-of-flight absorption images of ⁸⁴Sr and ⁸⁷Rb during evaporative cooling.

The Team

Benjamin Pasquiou, Alex Bayerle, Slava Tzanova, Simon Stellmer, Jacek Szczepkowski, Mark Parigger, Rudolf Grimm, and Florian Schreck

References

• Quantum degenerate mixtures of strontium and rubidium atoms: Phys. Rev. A 88, 023601 (2013), arXiv:1305.5935