  Based on the worm algorithm in the path-integral representation, we propose a
general quantum Monte Carlo algorithm suitable for parallelizing on a
distributed-memory computer by domain decomposition. Of particular importance
is its application to large lattice systems of bosons and spins. A large number
of worms are introduced and its population is controlled by a fictitious
transverse field. For a benchmark, we study the size-dependence of the
Bose-condensation order parameter of the hardcore Bose-Hubbard model with
$L\times L\times \beta t = 10240\times 10240\times 16$, using 3200 computing
cores, which shows good parallelization efficiency.

Statistical Mechanics