Multistep quantum master equation theory for response functions in four wave mixing electronic spectroscopy of multichromophoric macromolecules

TL;DR

This paper develops a multistep quantum master equation framework for calculating response functions in four wave mixing spectroscopy of multichromophoric systems, incorporating complex system-bath interactions and non-Markovian effects.

Contribution

It introduces a novel multistep quantum master equation approach for response function derivation, extending previous methods to include inter-exciton coupling and non-Markovian dynamics.

Findings

Closed form expressions for harmonic oscillator bath cases.

Feasible solution at 2nd order non-Markovian QME level.

Accounts for inter-exciton coupling, dephasing, and relaxation.

Abstract

This work provides an alternative derivation of third order response functions in four wave mixing spectroscopy of multichromophoric macromolecular systems considering only single exciton states. For the case of harmonic oscillator bath linearly and diagonally coupled to exciton states, closed form expressions showing all the explicit time dependences are derived. These expressions can provide more solid physical basis for understanding 2-dimensional electronic spectroscopy signals. For more general cases of system-bath coupling, the quantum master equation (QME) approach is employed for the derivation of multistep time evolution equations for Green function-like operators. Solution of these equations is feasible at the level of 2nd order non-Markovian QME, and the new approach can account for inter-exciton coupling, dephasing, relaxation, and non-Markovian effects in a consistent manner.