Mean-field phase diagram of cold lattice bosons in disordered potentials

Abstract

We show that a site-dependent mean-field approach captures the quantum phases of the disordered Bose-Hubbard model commonly adopted to describe ultracold bosons in random optical lattice potentials. The different phases, namely superfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal fluid, are characterized by means of the superfluid and condensate fractions, and compressibility of the system. We point out that both the boundaries of the Mott lobes and the nature of the phase surrounding them are related to the spectral features of a purely off-diagonal non-interacting Anderson model. We compare our results to other works.

5 pages, 4 figures, added some references and reformulated some sentences