Optical control of two-body scattering in Fermi gases

Traditionally, collisional interactions in ultra-cold gases have been tuned by an external magnetic field near a Feshbach resonance. Optical tuning techniques permit much finer temporal and spatial control of two-body scattering, enabling new studies of non-equilibrium phenomena. Optical methods are of particular interest in strongly interacting Fermi gases, which are stable near resonance. Unfortunately, single field optical control methods suffer from spontaneous scattering, which limits their utility. We are developing two-field optical control methods that employ quantum interference to greatly suppress spontaneous scattering. We will describe experiments using this method for broad and narrow Feshbach resonances in $^6$Li.