Canonical and grand canonical ensemble expectation values from quantum Monte Carlo simulations

We present a method for obtaining grand canonical expectation values as a continuous function of the chemical potential in quantum Monte Carlo simulations. We show how canonical ensemble expectation values can be extracted in such simulations. In order to obtain results for all particle sectors, a modest number of grand canonical simulations must be performed, each at a different chemical potential. With the canonical ensemble results in hand, grand canonical expectation values can be constructed for arbitrary dopings. Results are presented from the application of this method to the two-dimensional Hubbard model.