Cold atomic gas in an optical lattice: effects of coupling internal atomic states
KTH/Nordita/SU seminar in Theoretical Physics [before December 2013]
Wednesday 21 January 2009
to 12:00 at
Jonas Larson (Nordita)
In recent years, systems of cold atoms in optical lattices have drawn great interest. Due to their purity and high controllability of system parameters, they provide a salient model for the study of correlated many-body systems. In the milestone experiment by Bloch and co-workers, the first atomic phase transition between a Mott insulator state to a superfluid state was demonstrated. Such a transition derives from an interplay between atom-atom interaction and atomic kinetic energies.
In this talk I first consider the ground state of an ideal coupled two-component gas of ultracold atoms in a 1-D optical lattice, either bosons or fermions. In particular, I will show that despite lack of atom-atom interaction a first order phase transition is possible, originating from a competition between internal and external atomic degrees of freedom. In the case of fermions it is argued that the phase transition has a topological character. Secondly, I will consider interacting bosons and outline how coupling of internal atomic states modifies the Mott-superfluid phase diagram.