Dynamics of BEC mixtures loaded into the optical lattice in the presence of linear inter-component coupling

Abstract

We consider dynamics of a two-component Bose-Einstein condensate where the components correspond to different hyperfine states of the same sort of atoms. External microwave radiation leads to resonant transitions between the states. The condensate is loaded into the optical lattice. We invoke the tight-binding approximation and examine the interplay of spatial and internal dynamics of the mixture. It is shown that internal dynamics qualitatively depends on the intra-component interaction strength and the phase configuration of the initial state. We focus attention on two intriguing phenomena occurring for certain parameter values. The first phenomenon is the spontaneous synchronization of Rabi oscillations running inside neighbouring lattice sites. Another one is the demixing of the condensate with formation of immiscible solitons when nonlinearity becomes sufficiently strong. Demixing is preceded by the transient regime with highly irregular behavior of the mixture.