Periodically Dressed Condensates

Periodically Dressed Bose Condensates

In this proposed experimental project, we explore the consequences for a Bose condensate of a Raman coupling at finite momentum transfer between a pair of ground states. The Raman laser beams, tuned near resonance, produce a spatially periodic coupling between the components and thereby modify the dispersion relation of free atoms in the gas. Properties of a Bose-Einstein condensate formed in such a periodically-dressed gas are strongly affected by this modification to the dispersion relation. We make a Bogoliubov transformation which accounts for interparticle interactions to obtain the quasiparticle excitation spectrum in a Bose-Einstein condensate. The Landau critical velocity is found to be anisotropic and can be widely tuned by variations of the orientation, intensity, and relative detuning of the dressing laser beams. (See publications for our papers on the topic.)