Quantum simulations of the superfluid-insulator transition for   two-dimensional, disordered, hard-core bosons
  We introduce two novel quantum Monte Carlo methods and employ them to study the superfluid-insulator transition in a two-dimensional system of hard-core bosons. One of the methods is appropriate for zero temperature and is based upon Green's function Monte Carlo; the other is a finite-temperature world-line cluster algorithm. In each case we find that the dynamical exponent is consistent with the theoretical prediction of $z=2$ by Fisher and co-workers. 
Shiwei Zhang, N. Kawashima, J. Carlson, and J.E. Gubernatis