2 research outputs found
Stochastic Estimation with Noise
We introduce a noise for the stochastic estimation of matrix inversion
and discuss its superiority over other noises including the Gaussian noise.
This algorithm is applied to the calculation of quark loops in lattice quantum
chromodynamics that involves diagonal and off-diagonal traces of the inverse
matrix. We will point out its usefulness in its applications to estimating
determinants, eigenvalues, and eigenvectors, as well as its limitations based
on the structure of the inverse matrix.Comment: 6 pages, 1 postscript figure, UK/93-0
Phase diagrams, critical and multicritical behavior of hard-core Bose-Hubbard models
We determine the zero-temperature phase diagram of the hard-core Bose-Hubbard
model on a square lattice by mean-field theory supplemented by a linear
spin-wave analysis. Due to the interplay between nearest and next-nearest
neighbor interaction and cubic anisotropy several supersolid phases with
checkerboard, stripe domain or intermediate symmetry are stabilized. The phase
diagrams show three different topologies depending on the relative strength of
nearest and next-nearest neighbor interaction. We also find a rich variety of
new quantum critical behavior and multicritical points and discuss the
corresponding effective actions and universality classes.Comment: 19 pages, ReVTeX, 18 figures included, submitted to PR