The Rayleigh-Taylor Instability in a Bose-Einstein Condensate

We show how a two dimensional Bose-Einstein Condensate trapped in a nonequilibrium state can be driven into the Rayleigh-Taylor instability if an outward in-plane force is exerted on it. If the condensate is inside a semiconductor, the above force could arise from an inhomogeneous strain applied on the host semiconductor crystal. On the other hand, for a BEC of alkali atoms, the force could be exerted by an inhomogeneous magnetic field turned on after the BEC has been released from its magnetic trap. During its expansion, the condensate will break into droplets each a separate BEC. Therefore, one can create BEC droplets out of a single large BEC and study the coherence properties of the droplets with respect to each other. The discussion on the linear onset of the Rayleigh-Taylor instability in a BEC is generalized to three dimensions.