Nonequilibrium dynamics: Studies of the reflection of Bose-Einstein condensates

The study of nonequilibrium dynamics in Bose-Einstein condensed gases has been dominated by the zero-temperature mean field Gross-Pitaevskii formalism. Motivated by recent experiments on the reflection of condensates from silicon surfaces, we revisit the so called classical field description of condensate dynamics, which incorporates the effects of quantum noise and can also be generalized to include thermal effects. The noise is included in a stochastic manner through the initial conditions. We show that the inclusion of such noise is important in the quantitative description of the recent reflection experiments.