Heteronuclear Feshbach Resonances in Ultracold Mixtures of Ytterbium and Lithium

Thesis (Ph.D.)--University of Washington, 2019This thesis reports on experimental observation of heteronuclear Feshbach resonances between ultracold alkaline-earth-like Yb and alkali Li atoms, revealing methods for experimental control of heteronuclear scattering properties and strategies for coherent production of YbLi molecules. Optical Feshbach resonances are observed between Yb-174 and Li-6 through photoassociation (PA) spectroscopy. Two-photon PA spectroscopy of a series of the least-bound vibrational states in the YbLi electronic ground state provides an accurate description of the long-range interatomic potential and an accurate value of the s-wave scattering lengths between Yb and Li. A dark atom-molecule superposition state is created by optically dressing pairs of colliding atoms within an optically trapped bulk mixture and the feasibility of using such a state for coherent molecule production through stimulated Raman adiabatic passage is discussed. Magnetic Feshbach resonances (MFRs) between Yb-173 and Li-6 are observed. In the combination of closed-shell Yb and open-shell Li, MFRs are shown to stem from short-ranged hyperfine coupling between the unpaired Li electron spin and the Yb-173 nuclear spin, as demonstrated by analysis of Feshbach spectroscopy on ultracold mixtures in which both species are fully spin polarized. This work identifies two pathways for the coherent production of paramagnetic, polar molecules from a mixture of trapped Yb and Li: manipulation of either an optical or magnetic Feshbach resonance