Ytterbium and Lithium Quantum Gases: Heteronuclear Molecules and Bose-Fermi Superfluid Mixtures

Abstract

This dissertation describes a series of experiments conducted in an ultracold mixture of fermionic 6Li and bosonic 174Yb atoms, with a focus on the creation of heteronuclear YbLi molecules and the realization of a mixture of Bose and Fermi superfluids. Measurements of field-dependent inelastic scattering between metastable (3P2) Yb and ground state (2S1/2) Li are discussed, revealing the existence of interspecies Feshbach resonances which in principle may be used to create ultracold YbLi molecules in a coherent fashion, but in practice exhibit prohibitively large inelastic loss in the specific scattering channel used. An alternative all-optical two-photon pathway to ground state YbLi molecules is also explored, with the initial results presented here being the exploration of excited state YbLi molecular potentials using photoassociation spectroscopy, and the successful production of YbLi* molecules in a dual-species magneto-optical trap. An upgraded crossed optical dipole trap is implemented on the Yb-Li experimental apparatus, with a novel application of time-averaged potential shaping for very rapid and efficient Yb BEC production. Lastly, we detail the realization of an interacting mixture of Bose and Fermi superfluids, and identify the exchange of angular momentum between the superfluids by the excitation of a rotational mode of oscillation in the bosonic component due to interspecies interactions.