Nonequilibrium dynamics induced by miscible–immiscible transition in binary Bose–Einstein condensates

We have observed and characterized the nonequilibrium spatial dynamics of a two-component 87 Rb Bose–Einstein condensate (BEC) that is controllable switched back and forth between the miscible and immiscible phases of the phase separation transition by changing the internal states of the 87 Rb atoms. The subsequent evolution exhibits large scale oscillations of the spatial structure that involve component mixing and separation. We show that the larger total energy of the miscible system results in a higher oscillation frequency. This investigation introduces a new technique to control the miscibility and the spatial degrees of freedom in atomic BECs.