Self-energy renormalization for inhomogeneous nonequilibrium systems and field expansion via complete set of time-dependent wavefunctions

Y. Kuwahara, Y. Nakamura, Yoshiya Yamanaka

    Research output: Contribution to journalArticle

    Abstract

    The way to determine the renormalized energy of inhomogeneous systems of a quantum field under an external potential is established for both equilibrium and nonequilibrium scenarios based on thermo field dynamics. The key step is to find an extension of the on-shell concept valid in homogeneous case. In the nonequilibrium case, we expand the field operator by time-dependent wavefunctions that are solutions of the appropriately chosen differential equation, synchronizing with temporal change of thermal situation, and the quantum transport equation is derived from the renormalization procedure. Through numerical calculations of a triple-well model with a reservoir, we show that the number distribution and the time-dependent wavefunctions are relaxed consistently to the correct equilibrium forms at the long-term limit.

    Original languageEnglish
    Article number1850111
    JournalInternational Journal of Modern Physics B
    Volume32
    Issue number10
    DOIs
    Publication statusPublished - 2018 Apr 20

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    expansion
    differential equations
    operators
    energy

    Keywords

    • cold atom
    • nonequilibrium
    • Quantum field theory
    • quantum transport equation
    • renormalization
    • thermo field dynamics

    ASJC Scopus subject areas

    • Statistical and Nonlinear Physics
    • Condensed Matter Physics

    Cite this

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    abstract = "The way to determine the renormalized energy of inhomogeneous systems of a quantum field under an external potential is established for both equilibrium and nonequilibrium scenarios based on thermo field dynamics. The key step is to find an extension of the on-shell concept valid in homogeneous case. In the nonequilibrium case, we expand the field operator by time-dependent wavefunctions that are solutions of the appropriately chosen differential equation, synchronizing with temporal change of thermal situation, and the quantum transport equation is derived from the renormalization procedure. Through numerical calculations of a triple-well model with a reservoir, we show that the number distribution and the time-dependent wavefunctions are relaxed consistently to the correct equilibrium forms at the long-term limit.",
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    AU - Nakamura, Y.

    AU - Yamanaka, Yoshiya

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    KW - quantum transport equation

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    KW - thermo field dynamics

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