Our main program is in the area of atom cooling and trapping, which is currently focused on the study of atomic fermions. The central feature of our program is the use of all-optical methods to achieve quantum degeneracy. Our experiments employ an optical trap which consists of a single focused beam from a high-power ultrastable CO2 laser. Atoms are attracted to the highest intensity region near the focal point, where a potential well is formed. By employing an ultrahigh vacuum, trap lifetimes of 400 seconds are achieved. Forced evaporation in the optical trap is used to achieve quantum degeneracy.
The all-optical approach is ideally suited to exploring atomic gases with magnetically tunable interactions, as used in our experiments. Thus we can produce a Fermi gas with an interaction strength which can be tuned from zero to very strongly attractive or repulsive. We were the first group to realize a strongly interacting degenerate fermi gas in the BEC-BCS crossover region. Surprisingly, this strongly interacting atomic gas shares similarities to many other systems in nature, such as high-temperature superconductors, neutron stars, and the quark-gluon plasma. We were also the first group to observe evidence for superfluid hydrodynamics. Our research program strives to make precise and model-independent measurements to aid in the theoretical understanding of these systems.
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