Mott Insulator-Superfluid transition with cold atoms trapped in optical lattice

Abstract

We study the superfluid-Mott insulator quantum phase transition for ultracold atoms described by the Bose-Hubbard model. We first analyse the limiting regimes where only kinetic or interaction energies are present, corresponding to a superfluid (delocalized) or a Mott-insulator (localized) state, respectively. Using a variational wave-function, where the different sites are decorrelated, and imaginay time propagation we then interpolate between these two cases, and find the full phase diagram of the model by analysing the superfluid order parameter, and the average and variance of density of particles per site