Supervisor: Vittorio Penna
We consider mixtures of ultracold bosons formed by two atomic species, and investigate the properties of the ground state and of weakly-excited states. We explore the quantum phases of the mixture in the zero-temperature regime, its miscibility properties and, more in general, the formation of spatially complex configurations caused by the interplay of species densities, interspecies and intraspecies interactions, and tunneling effects.
This study includes the influence of the trapping geometry and model parameters on
- the critical properties of the phase diagram for (planar, ring ladder, multi-ring) optical lattices described in the Bose-Hubbard (BH) picture
- the emergence of dynamical instability regimes in their mean-field representation.
Mixtures are also studied in 2D and 3D continuous media, within the Gross-Pitaevskii picture, where soliton-vortex states appear due to the demixing effect. Their rich phenomenology, represented in terms of Lorentz-like equations for pointlike vortices, is studied together with the extension to vortex-string state in 3D domains.