Non-Hermitian Floquet dynamics in absorption spectroscopy

TL;DR

This paper develops a theoretical framework for absorption spectroscopy in media interacting with strong electromagnetic fields, utilizing non-Hermitian Floquet Hamiltonians to describe the system's dynamics without the rotating wave approximation.

Contribution

It introduces a novel approach to analyze absorption in strongly driven media using non-Hermitian Floquet theory, extending beyond traditional approximations.

Findings

Reduced Lindblad equations for steady state coherences

Expressed complex susceptibility via decaying dressed states

Applicable to atomic and condensed matter systems

Abstract

A theory of the absorption of a laser field by an atomic or condensed matter medium is presented for the case where the medium is also interacting with a strong electromagnetic field. The rotating wave approximation is not assumed for the latter. It is shown that in the weak probe limit the Lindblad master equation reduces to a smaller system of linear equations for the relevant steady state coherences. In this limit, the complex susceptibility of the medium can be expressed in terms of individual contributions of decaying dressed states, the latter being eigenstates of a non-Hermitian Floquet Hamiltonian.