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Nonequilibrium nonlinear open quantum systems: Functional perturbative analysis of a weakly anharmonic oscillator

TitleNonequilibrium nonlinear open quantum systems: Functional perturbative analysis of a weakly anharmonic oscillator
Publication TypeJournal Article
Year of Publication2020
AuthorsJ-T. Hsiang, and B-L. Hu
JournalPhys. Rev. D
Volume101
Date Publishedjun
ISSN1550-7998
Abstract

We introduce a functional perturbative method for treating weakly nonlinear systems coupled with a quantum field bath. We demonstrate using this method to obtain the covariance matrix elements and the correlation functions of a quantum anharmonic oscillator interacting with a heat bath. We identify a fluctuation-dissipation relation based on the nonequilibrium dynamics of this nonlinear open quantum system. To establish its connection with dynamical equilibration, we further examine the energy flows between the anharmonic oscillator and the bath field. The vanishing of the net flow is an indication of the existence of an equilibrium state for such an open-system configuration. The results presented here are useful for studying the nonequilibrium physical processes of nonlinear quantum systems such as heat transfer or electron transport.

DOI10.1103/PhysRevD.101.125002