Gaussian quantum Monte Carlo methods for fermions and bosons

A novel class of quantum Monte Carlo methods, which were based on a Gaussian quantum operator representation of fermionic states was investigated. The finite-temperature properties of the two dimensional Hubbard model and the dynamics in a simple model of coherent molecular dissociation were calculated as an application relevant to the Fermi sign problem. The identities for first-principles calculations of the time evolution of quantum systems, both dynamical and canonical were also discussed. The results show that many-body quantum systems map exactly to stochastic equations if a suitable stochastic gage is chosen which eliminates all boundary terms.