Phase transition of the ground state for two-component Bose-Einstein condensates in a triple-well trap

We consider the ground-state structure of two-component Bose-Einstein condensates trapped in a triple-well potential. We observe three structural phases of self-trapping, phase separation and symmetry state phase, which reflect the interplay of the intraspecies and interspecies interactions. We also show that the transitions from the self-trapping phase to the symmetry phase and from the phase separation to the symmetry phase are first-order phase transitions, while the transition from the self-trapping phase to the phase separation phase is a continuous one.