Classical-field method for time dependent Bose-Einstein condensed gases - art. no. 210404

We propose a method to study the time evolution of Bose-Einstein condensed gases perturbed from an initial thermal equilibrium, based on the Wigner re presentation of the N-body density operator. We show how to generate a coll ection of random classical fields sampling the initial Wigner distribution in the number conserving Bogoliubov approximation. The fields are then evol ved with the time dependent Gross-Pitaevskii equation, We illustrate the me thod with the damping of a collective excitation of a one-dimensional Bose gas.