Nonequilibrium dynamics of optical-lattice-loaded Bose-Einstein-condensate atoms: Beyond the Hartree-Fock-Bogoliubov approximation

Abstract

The nonequilibrium dynamics of a Bose-Einstein condensate selectively loaded into every third site of a one-dimensional optical lattice was discussed. A two-particle irreducible (2PI) closed-time-path (CTP) effective action was used for the purpose. Three different approximations under the 2PI CTP scheme were considered. The comparisons between these approximations were presented and their range of validity by contrasting them with the exact many-body solution for a moderate number of atoms and wells was determined.