SIMULATIONS OF DISCRETE QUANTUM-SYSTEMS IN CONTINUOUS EUCLIDEAN TIME

We propose a new method to study path integrals for discrete quantum s ystems, in which we work directly in the Euclidean time continuum. The method is applied here to the Heisenberg quantum antiferromagnet usin g a continuous-time version of a loop cluster algorithm. This algorith m is exploited to confirm the predictions of chiral perturbation theor y in the extreme low temperature regime, down to T = 0.01J. A fit of t he low-energy parameters of chiral perturbation theory gives excellent agreement with previous results and with experiments.