Optomechanics of ultracold atomic gases

We give a brief overview of the basic aspects of the optomechanical interaction between a light field and a mechanical mode of ultracold bosonic and fermionic atomic gases inside a Fabry-Pérot cavity, showing that these systems provide a 'bottom up' approach to cavity optomechanics. In contrast to the case of a Bose condensate, where the effective 'moving mirror' is a side mode whose occupation results simply from photon recoil, for fermionic atoms this 'mirror' is a collective density oscillation associated with particle-hole excitations. We also discuss the experimental consequences of the optomechanical coupling in optical bistability.