Dual quantum Monte Carlo algorithm for hardcore bosons

We derive the exact dual representation of the bosonic Hubbard model which takes the form of conserved current loops. The hardcore limit, which corres ponds to the quantum spin-1/2 Heisenberg antiferromagnet, is also obtained. In this limit, the dual partition function takes a particularly simple for m which is very amenable to numerical simulations. In addition to the usual quantities that we can measure (energy, density-density correlation functi on and superfluid density) we can with this new algorithm measure efficient ly for the first time the order parameter correlation function, [a(i)n(j)(d agger)], \i - j\ greater than or equal to 1. We demonstrate this with numer ical tests in one dimension. (C) 1999 Elsevier Science B.V. All rights rese rved.