Equivalence of kinetic theories of Bose-Einstein condensation - art. no. 053612

We discuss the equivalence of two nonequilibrium kinetic theories that desc ribe the evolution of a dilute. Bose-Einstein condensed atomic gas in a har monic trap. The second-order kinetic equations of Walser et al. [Phys. Rev. A 63, 013607 (2001)] reduce to the Gross-Pitaevskii equation and the quant um Boltzmann equation in the low- and high-temperature limits, respectively , These kinetic equations thus describe the system in equilibrium (finite t emperature) as well as in nonequilibrium (real time). We have found this th eory to be equivalent to the nonequilibrium Green's function approach origi nally proposed by Kadanoff and Baym and more recently applied to inhomogene ous trapped systems by Imamovic-Tomasovic and Griffin [in Progress in Noneq uilibrium Green's Functions, edited by M. Bonitz (World Scientific, Singapo re, 2000), p. 404].