title: Decoherence and thermalization of a pure quantum state in quantum field theory.
abstract: We study the real-time evolution of a self-interacting O(N) scalar field initially prepared in a pure, coherent quantum state. We present a complete solution of the nonequilibrium quantum dynamics from a 1/N expansion of the two-particle-irreducible effective action at next-to-leading order, which includes scattering and memory effects. We demonstrate that, restricting one's attention (or ability to measure) to a subset of the infinite hierarchy of correlation functions, one observes an effective loss of purity or coherence and, on longer time scales, thermalization. We point out that the physics of decoherence is well described by classical statistical field theory.
authors.affiliation: Astro-Particule et Cosmologie, Université Paris 7-Denis Diderot, 10 rue A. Domont et L. Duquet, 75205 Paris cedex 13, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Giraud
authors.forename: Julien
authors.initials: J
authors.lastname: Serreau