Coherently driven 2-component Bose gases
Alessio Recati (Università di Trento, Italia)
In the present talk I will give an overview on the physics of 2-component Bose gases in presence of an spin exchange – Rabi – term. The Rabi term reduces the gauge symmetry of the system and a gap opens for relative phase excitations. The latter has many consequences. In particular it leads to the formation of vortex dimers coupled through sine-Gordon solitons. Results on the dynamics of the vortex dimer are presented. The system exhibits also a second order (quantum) phase transition between a neutral (paramagnetic) and a polarised (ferromagnetic) state, provided the interspecies interaction is large enough. I will discuss some phenomena related to the phase transition and to the two phases and the interplay between Rabi coupling and density-density interaction:
(i) at a mean-field level for a continuous model – which well described atoms in a shallow trap.
(ii) for a one-dimensional single band Hubbard model – which should properly describe atoms confined in an one-dimensional optical lattice.