Experimental Evidence for the Breakdown of a Hartree-Fock Approach in a Weakly Interacting Bose Gas

J.-B. Trebbia, J. Esteve, C. I. Westbrook, I. Bouchoule
2006 Physical Review Letters  
We study the formation of a quasi-condensate in a nearly one dimensional, weakly interacting trapped atomic Bose gas. We show that a Hartree Fock (mean-field) approach fails to explain the presence of the quasi-condensate in the center of the cloud: the quasi-condensate appears through an interaction-driven cross-over and not a saturation of the excited states. Numerical calculations based on Bogoliubov theory give an estimate of the cross-over density in agreement with experimental results.
doi:10.1103/physrevlett.97.250403 pmid:17280332 fatcat:7wlinokgcjeproruh5xfr6sn3e