Proper treatment of the zero mode in quantum field theory for trapped Bose-Einstein condensation

M. Okumura, Yoshiya Yamanaka

    Research output: Contribution to journalArticlepeer-review

    Abstract

    So far much theoretical consideration of experiments on the Bose-Einstein condensation (BEC) of alkali-metal atoms in harmonic traps is based on the Gross-Pitaevskii (GP) equation. In this paper, we attempt to formulate the BEC in the language of quantum field theory and to estimate the quantum and thermal fluctuation effects, which are neglected in the approximation using the GP equation. First, the formulation at zero temperature is developed, and then it is extended to the finite-temperature case by means of thermofield dynamics. We treat the zero-energy mode with care, so that the canonical commutation relations hold. As a result, an infrared divergence appears, but it can be renormalized into the observed condensate number. Numerical calculations are performed. For illustration, the corrections at one-loop level to the original GP equation are given. We also calculate numerically the effects of quantum and thermal fluctuations on the distribution of condensed atoms.

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

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics

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