BCS-BEC crossover in a spin-orbit coupled Fermi gas

It is generally believed that a BCS-BEC crossover can be realized in fermionic systems by tuning the attraction strength. Recent experimental breakthrough in generating artificial non-Abelian gauge field has opened up the opportunity to study the spin-orbit coupling effects in cold atomic gases. In this talk, I will discuss another route to realize the BCS-BEC crossover. By tuning the spin-orbit coupling strength in an atomic Fermi gas, we can realize a crossover from the ordinary BCS/BEC superfluid to the Bose-Einstein condensate of a novel type of bound state, called rashbon. Various properties of this crossover, such as the superfluid density, the condensate fraction, the transition temperature, and the collective modes are studied. At large spin-orbit coupling, the properties of the superfluid are universal, that is, independent of the initial attractive interaction (or s-wave scattering length).