Quasicondensate and superfluid fraction in the two-dimensional charged boson gas at finite temperature - art. no. 104509

The Bogoliubov-de Gennes equations are solved for the Coulomb Bose gas desc ribing a fluid of charged bosons at finite temperature. The approach is app licable in the weak-coupling regime and the extent of its quantitative usef ulness is tested in the three-dimensional fluid, for which diffusion Monte Carlo data are available on the condensate fraction at zero temperature. Th e one-body density matrix is then evaluated by the same approach for the tw o-dimensional fluid with e(2)/r interactions, to demonstrate the presence o f a quasi condensate from its power-law decay with increasing distance and to evaluate the superfluid fraction as a function of temperature at weak co upling.