Zero-temperature phase diagram of hard sphere bosons in asymmetric three   dimensional optical lattices
  We studied the superfluid-to-Mott insulator transition for bosonic hard spheres loaded in asymmetric three-dimensional optical lattices by means of diffusion Monte Carlo calculations. The onset of the transition was monitored through the change in the chemical potential around the density corresponding to one particle per potential well. With this method, we were able to reproduce the results given in the literature for three-dimensional symmetric lattices and for systems whose asymmetry makes them equivalent to a set of quasi-one dimensional tubes. The location of the same transition for asymmetric systems akin to a stack of quasi-two dimensional lattices will be also given. Our results were checked against those given by a Bose-Hubbard model for similar arrangements. 
F. De Soto, C. Carbonell-Coronado and M.C. Gordillo
cond-mat.quant-gas