Kinetic transport theory with quantum coherence

TL;DR

This paper develops a quantum kinetic transport framework incorporating coherence effects for fermions and bosons, providing a self-consistent way to describe how quantum coherence influences thermalization and decoherence in noninteracting and interacting systems.

Contribution

It introduces a novel phase space structure with singular shells to encode quantum coherence in transport equations derived via the Schwinger-Keldysh formalism.

Findings

Coherence information is represented by new singular shells in the 2-point function.

The derived equations describe how coherence affects thermalization and decoherence.

Application to out-of-equilibrium states shows approach to equilibrium with coherence effects included.

Abstract

We derive transport equations for fermions and bosons in spatially or temporally varying backgrounds with special symmetries, by use of the Schwinger-Keldysh formalism. In a noninteracting theory the coherence information is shown to be encoded in new singular shells for the 2-point function. Imposing this phase space structure to the interacting theory leads to a a self-consistent equation of motion for a physcial density matrix, including coherence and a well defined collision integral. The method is applied e.g. to demonstrate how an initially coherent out-of-equlibrium state approaches equlibrium through decoherence and thermalization.