Heteronuclear quantum gas mixtures

TL;DR

This paper reviews experiments on heteronuclear quantum gas mixtures, highlighting the creation of large quantum degenerate mixtures, tunable interactions, phase control, and the first realization of ultracold heteronuclear Feshbach molecules.

Contribution

It presents new experimental techniques for creating and controlling heteronuclear quantum gases, including Feshbach resonances and lattice-based molecule formation.

Findings

Achieved large quantum degenerate 40K-87Rb mixtures.

Demonstrated tunable interactions inducing phase separation and collapse.

First realization of ultracold heteronuclear Feshbach molecules.

Abstract

This PhD tutorial article is a review of our experiments on heteronuclear quantum gas mixtures at the University of Hamburg. We introduce basic properties of trapped Fermi-Bose mixtures and demonstrate the achievement of large quantum degenerate mixtures of 40K and 87Rb. Using heteronuclear Feshbach resonances, we show how the heteronuclear interaction can be tuned, allowing us to induce phase separation and collapse for large repulsive and attractive interactions, respectively. We realize Fermi-Bose mixtures in 3D optical lattices as a novel quantum many-body system and study coherence properties of the mixture. Combining our experiments on lattices and Feshbach resonances, we present the first realization of ultracold heteronuclear Feshbach molecules. The molecules are created at individual sites of a 3D optical lattice. We discuss lifetime, binding energy and rf association efficiency in terms of a universal model and give an outlook for possible future developments.