Rotating-Wave and Secular Approximations for Open Quantum Systems

TL;DR

This paper derives bounds on the accuracy of common approximations in open quantum systems, such as the rotating-wave and secular approximations, especially under dissipation and strong coupling.

Contribution

It provides a nonperturbative bound on the evolution difference and error estimates for these approximations in open quantum systems.

Findings

Explicit upper bound on the error of the rotating-wave approximation with dissipation.

Bound applied to strong-coupling limit in open quantum systems.

Analysis of secular approximation in deriving master equations.

Abstract

We derive a nonperturbative bound on the distance between evolutions of open quantum systems described by time-dependent generators. We show how this result can be employed to provide an explicit upper bound on the error of the rotating-wave approximation in the presence of dissipation and decoherence. We apply the derived bound to the strong-coupling limit in open quantum systems and to the secular approximation used to obtain a master equation from the Redfield equation.