Quantum degenerate mixtures of alkali and alkaline-earth-like atoms

TL;DR

This paper reports the creation of quantum degenerate mixtures of alkali and alkaline-earth-like atoms Li and Yb, enabling new studies in ultracold molecules, Efimov trimers, and superfluid systems.

Contribution

First realization of simultaneous quantum degeneracy in Li-Yb mixtures and measurement of their elastic scattering lengths.

Findings

Achieved quantum degeneracy in Li and Yb mixtures.

Measured Li-Yb s-wave scattering lengths (~1 nm).

Found scattering lengths consistent with mass-scaling analysis.

Abstract

We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkalineearth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope 6Li with evaporatively cooled bosonic 174Yb and, separately, fermionic 173Yb.Using cross-thermalization studies, we also measure the elastic s-wave scattering lengths of both Li-Yb combinations, |a6Li-174Yb| = 1.0\pm0.2 nm and |a6Li-173Yb| = 0.9\pm0.2 nm. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.