Two-Element Mixture of Bose and Fermi Superfluids
April 20, 2017 -
3:00pm to 4:00pm
University of Washington
By combining ultracold gases of two different elements, new quantum systems may be explored. I will present our realization of a two-element mixture of Bose and Fermi superfluids, a system out of reach with liquid helium mixtures. We use bosonic ytterbium and fermionic lithium, which feature a strong mismatch in mass and distinct electronic properties, and demonstrate elastic coupling between the superfluids by observing the shift in dipole oscillation frequency of the bosonic component due to the presence of the fermions.
The measured magnitude of the shift is consistent with a mean-field model and its direction determines the previously unknown sign of the interspecies scattering length to be positive. We also observe the exchange of angular momentum between the superfluids from the excitation of a scissors mode in the bosonic component through interspecies interactions. I will also briefly report on efforts in our group towards combining lithium and ytterbium to produce ultracold polar molecules with a spin degree of freedom.