Spin Mixing Dynamics in a Spin–Orbit Coupled Bose–Einstein Condensate

Abstract

We investigate the spin mixing dynamics of a spin–orbit coupled Bose–Einstein condensate by using a variational approach. It is shown that the spin mixing dynamics can be well described by an internal Josephson equation. In the nonzero momentum phase, the spin mixing dynamics leads to a spin polarization, i.e., most atoms are suppressed in the one of the two spin states. In the zero momentum phase, the internal Josephson oscillation between the two spin states takes place. Thus, the coupling effects of spin–orbit coupling, Raman coupling and atomic interaction can result in the transition between the spin polarization and the internal Josephson oscillation of the two spin states, which provide a theoretical evidence for elaborating the spin mixing dynamics. Moreover, at the phase transition point, the oscillation period of the spin mixing dynamics tends to infinity. This can be used to explore the phase transition experimentally. The accurate manipulation of the spin mixing dynamics can provide a theoretical evidence for designing the atomic device.