Bose-Glass to Superfluid Transition in the 3d Boson Hubbard Model: z=d

Jens Kisker, Heiko Rieger

Botao Wang, Ying Jiang

Jens Kisker, Heiko Rieger

We investigate the Bose glass phase and the insulator-to-superfluid transition in the two-dimensional disordered Boson Hubbard model in the Villain representation via Monte Carlo simulations. In the Bose glass phase the probability distribution of the local susceptibility is found to have a 1χ2 tail and the imaginary time Green's function decays algebraically C(τ) ≈ τ−1 giving rise to a divergent global susceptibility. By considering the participation ratio it is shown that the excitations in the Bose glass phase are fully localized and a scaling law is established. For commensurate Boson densities we find direct Mott insulator to superfluid transition without an intervening Bose glass phase for weak disorder. For this transition we obtain the critical exponents z = 1, v = 0.7 ± 0.1 and η = 0.1 ± 0.1, which agree with those for the classical three-dimensional XY model without disorder. This indicates that disorder is irrelevant at the tip of the Mott-lobes and that here the inequality v⩾2d is violated.

Владимир Федорович Елесин, V. А. Kashurnikov, L. А. Openov

Naomichi Hatano

Superfluid-insulator transitions are studied for the ground state of the Boson Hubbard model with random potentials. The topology of the phase diagram is discussed. Reentrant transitions between the superfluid phase and the Bose-glass insulator phase are found in an arbitrary number of dimensions. The present results are based on a perturbational scaling argument and a quantum Monte Carlo calculation. The Monte Carlo algorithm is also reported in detail.

Bernhard Wünsch, David Pekker, Takuya Kitagawa +2 more