Non-Hermitian wave packet approximation for coupled two-level systems in weak and intense fields

TL;DR

This paper presents a non-Hermitian wave packet approximation that simplifies the simulation of two-level quantum systems under various laser field intensities, accurately capturing excitation, relaxation, and decoherence effects.

Contribution

It introduces a novel non-Hermitian Schrödinger-type method that replaces density matrix propagation, incorporating relaxation and dephasing through dynamic gain and decay rates.

Findings

Accurately models excitation, relaxation, and decoherence dynamics.

Simplifies calculations by propagating wave functions instead of density matrices.

Effectively describes scattering and absorption in layered two-level systems.

Abstract

We introduce an accurate non-Hermitian Schr\"odinger-type approximation of Bloch optical equations for two-level systems. This approximation provides a complete description of the excitation, relaxation and decoherence dynamics in both weak and strong laser fields. In this approach, it is sufficient to propagate the wave function of the quantum system instead of the density matrix, providing that relaxation and dephasing are taken into account via automatically-adjusted time-dependent gain and decay rates. The developed formalism is applied to the problem of scattering and absorption of electromagnetic radiation by a thin layer comprised of interacting two-level emitters.