1997/09/29 by A. Minguzzi, A Minguzzi, M. P. Tosi +1 · 5 citations
Chemistry · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Cold Atom Physics and Bose-Einstein Condensates #Quantum many-body systems #cond-mat.stat-mech
paper · pdf · doi:10.1088/0953-8984/9/46/019
published as J. Phys: Condens. Matter vol. 9, p. 10211 (1997) · 14 pages. To appear on J. Phys. : Condens. Matter
arxiv created 1997/09/29 · openalex publication_date 1997/11/17 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
A linear response framework is set up for the evaluation of collective excitations in a confined vapour of interacting Bose atoms at finite temperature. Focusing on the currently relevant case of contact interactions between the atoms, the theory is developed within a random-phase approximation with exchange. This approach is naturally introduced in a two-fluid description by expressing the density response of both the condensate and the non-condensate in terms of the response of a Hartree - Fock reference gas to the self-consistent Hartree - Fock potentials. Such an approximate account of correlations (i) preserves an interplay between the condensate and the non-condensate through off-diagonal components of the response, which instead vanish in the Hartree - Fock - Bogoliubov approximation; and (ii) yields a common resonant structure for the four partial response functions. The theory reduces to the temperature-dependent Hartree - Fock - Bogoliubov - Popov approximation for the fluctuations of the condensate when its coupling with the density fluctuations of the non-condensate is neglected. Analytic results are presented which are amenable to numerical calculations and to inclusion of damping rates.