Stochastic scattering theory for excitation induced dephasing: Comparison to the Anderson-Kubo lineshape

TL;DR

This paper introduces a quantum stochastic model for spectroscopic line-shapes affected by a dynamic background of excitations, highlighting differences from classical models in lineshape asymmetry and background dependence.

Contribution

It develops a novel quantum stochastic framework for excitation-induced dephasing, incorporating non-stationary backgrounds and comparing it to classical Anderson-Kubo lineshape models.

Findings

The model predicts asymmetric lineshapes not captured by classical models.

Line-shape variations increase with background population.

The approach provides a new way to analyze excitation-induced dephasing.

Abstract

In this paper we present a quantum stochastic model for spectroscopic line-shapes in the presence of a co-evolving and non-stationary background population of excitations. Starting from a field theory description for interacting bosonic excitons, we derive a reduced model whereby optical excitons are coupled to an incoherent background via scattering as mediated by their screened Coulomb coupling. The Heisenberg equations of motion for the optical excitons are then driven by an auxiliary stochastic population variable, which we take to be the solution of an Ornstein-Uhlenbeck process. It\^o's Lemma then allows us to easily construct and evaluate correlation functions and response functions. Focusing on the linear response, we compare our model to the classic Anderson-Kubo model. While similar in motivation, there are profound differences in the predicted lineshapes, notably in terms of asymmetry, and variation with increasing background population.