Sympathetic cooling in an optically trapped mixture of alkali and spin-singlet atoms

TL;DR

This paper demonstrates stable ultracold mixtures of lithium and ytterbium atoms in an optical trap, achieving sympathetic cooling of lithium via ytterbium and reaching temperatures below the Fermi temperature.

Contribution

It reports the first realization of a stable alkali and spin-singlet atom mixture with measured inter-species scattering length and demonstrates effective sympathetic cooling to quantum degeneracy.

Findings

Measured the inter-species scattering length |a6Li-174Yb| = (13 ± 3)a0.

Achieved cooling of lithium below the Fermi temperature through sympathetic cooling.

Established stability of the ultracold mixture in an optical trap.

Abstract

We report on the realization of a stable mixture of ultracold lithium and ytterbium atoms confined in a far-off-resonance optical dipole trap. We observe sympathetic cooling of 6Li by 174Yb and extract the s-wave scattering length magnitude |a6Li-174Yb| = (13 \pm 3)a0 from the rate of inter-species thermalization. Using forced evaporative cooling of 174Yb, we achieve reduction of the 6Li temperature to below the Fermi temperature, purely through inter-species sympathetic cooling.