Perturbation theory of spin-1 Bose-Einstein condensates

Shingo Ohtsuka, Susumu Kurihara

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    Abstract

    We generalize the perturbation theory of weakly interacting bosons to Bose-Einstein condensates with hyperfine spin [Formula Presented] Analytical expressions of second-order self-energies beyond the mean-field approximation are derived at zero temperature. We further extend the perturbation theory to the finite-temperature case, and derive the corresponding self-energies. We evaluate these self-energies near the poles of the first-order (mean-field) Green’s functions within the on-shell approximation, and expand the results in powers of wave number in the long-wavelength limit. Excitation spectra for each mode are obtained analytically at low temperatures. We also derive the ground-state energy and thermodynamic quantities such as free energy of the system.

    Original languageEnglish
    Number of pages1
    JournalPhysical Review A - Atomic, Molecular, and Optical Physics
    Volume68
    Issue number1
    DOIs
    Publication statusPublished - 2003 Jan 1

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    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics

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