title: Sampling from the thermal quantum Gibbs state and evaluating partition functions with a quantum computer.
abstract: We present a quantum algorithm to prepare the thermal Gibbs state of interacting quantum systems. This algorithm sets a universal upper bound D(alpha) on the thermalization time of a quantum system, where D is the system's Hilbert space dimension and alpha < or = 1/2 is proportional to the Helmholtz free energy density. We also derive an algorithm to evaluate the partition function of a quantum system in a time proportional to the system's thermalization time and inversely proportional to the targeted accuracy squared.
authors.affiliation: Département de Physique, Université de Sherbrooke, Québec, Canada, J1K 2R1.
authors.forename: David
authors.initials: D
authors.lastname: Poulin
authors.forename: Pawel
authors.initials: P
authors.lastname: Wocjan