Ultracold Rb/Yb Mixtures

Mixtures of ultracold atoms provide a range of opportunities for cold atom research beyond single-species experiments. In this project we use mixtures of 87Rb and Yb atoms to study quantum gas mixtures. Ytterbium is particularly attractive because there are seven stable isotopes (including five bosonic species and two fermionic species with nuclear spin 1/2 and 5/2), allowing for study of Bose-Bose and Bose-Fermi mixtures. The atomic structure of 171Yb allows for novel optical potentials with sub-wavength structure, as well as detection of the atomic wavefunction with sub-wavelength resolution. In addition, RbYb ground state molecules have potentially large electric dipole moments, allowing for long range interactions. There are a variety of possible research avenues open to this system, but our initial goals are to use a rubidium Bose-Einstein condensate as a "bath" to provide controlled dissipation for ytterbium trapped in a Rb-blind optical lattice. Much as laser cooling uses scattering of optical photons to cool atoms well below room temperature, here the high energy modes of the rubidium condensate would act as a scattering mode to cool the ytterbium below the rubidium temperature. Engineered coupling to such dissipative modes may provide new methods for producing low-entropy states. This research is being carried out at the Joint Quantum Institute on the Atlantic building at the University of Maryland campus.