We address computational issues relevant to the study of disordered quantum mechanical systems at very low temperatures. As an example we consider the disordered BoseHubbard model in three dimensions directly at the Boseglass to superfluid phase transition. The universal aspects of the critical behaviour are captured by a (3 + 1) dimensional link-current model for which an efficient ‘worm’ algorithm is known. We present a calculation of the distribution of the superfluid stiffness over the disorder realizations, outline a number of important considerations for performing such estimates, and suggest a modification of the linkcurrent Hamiltonian that improves the numerical efficiency of the averaging procedure without changing the universal properties of the model.
Peter Hitchcock, Erik S. Sørensen