Localized spin states in conventional superconductors at low temperatures are expected to have a long decoherence time due to the strong suppression of spin relaxation channels. We propose a scanning… (More)

The scaling of the conductivity at the superfluid-insulator quantum phase transition in two dimensions is studied by numerical simulations of the Bose-Hubbard model. In contrast to previous studies,… (More)

We generalize the imaginary-chemical-potential quantum Monte Carlo (QMC) method proposed by Dagotto [Phys. Rev. B 41, R811 (1990)] to systems without particle-hole symmetry. The generalized method is… (More)

We determine the quantum phase diagram of a two-dimensional bosonic t-Jz model as a function of the lattice anisotropy gamma, using a quantum Monte Carlo loop algorithm. We show analytically that the… (More)

We study the binding of a holon and a spinon in the one-dimensional anisotropic t-J model using a Bethe-Salpeter equation approach, exact diagonalization, and density matrix renormalization group… (More)

An efficient quantum Monte Carlo algorithm for the simulation of bosonic systems on a lattice in a grand canonical ensemble is proposed. It is based on the mapping of bosonic models to the spin… (More)