2005/09/30 by C. -H. Zhang, C.-H. Zhang, H. A. Fertig
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #Quantum, superfluid, helium dynamics #cond-mat.mes-hall
paper · pdf · doi:10.1103/physreva.74.023613
2 figure. Submitted to PRA
arxiv created 2006/04/27 · openalex publication_date 2006/08/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We develop a time-dependent Hartree-Fock approximation that is appropriate for Bose-condensed systems. Defining a depletion Green's function allows the construction of condensate and depletion particle densities from eigenstates of a single time-dependent (oscillating) Hamiltonian, guaranteeing that our approach is a number-conserving approximation. The poles of this Green's function yield the energies of number-changing excitations for which the condensate particle number is held fixed, which we show has a gapped spectrum in the superfluid state. The linearized time-dependent version of this has poles at the collective frequencies of the system, yielding the expected zero sound mode for a uniform infinite system. We show how the approximations may be expressed in a general linear response formalism.