Calculations of coherent two-dimensional electronic spectra using forward and backward stochastic wavefunctions

TL;DR

This paper introduces a stochastic wavefunction approach within the optical response function formalism to efficiently compute 2D electronic spectra, providing insights into environmental effects on quantum coherence in complex systems.

Contribution

It presents a novel forward-backward stochastic Schrödinger equation method for 2D spectra calculation, reducing computational cost and enabling analysis of large-scale photosynthetic systems.

Findings

The method accurately reproduces spectra compared to deterministic approaches.

Environmental damping significantly influences quantum coherence lifetimes.

The scheme offers a scalable tool for studying quantum effects in complex systems.

Abstract

Within the well-established optical response function formalism, a new strategy with the central idea of employing the forward-backward stochastic Schr\"{o}dinger equations in a segmented way to accurately obtain the two-dimensional (2D) electronic spectrum is presented in this paper. Based on the simple excitonically coupled dimer model system, the validity and efficiency of the proposed schemes are demonstrated in detail, along with the comparison against the deterministic hierarchy equations of motion and perturbative second order time-convolutionless quantum master equations. In addition, an important insight is provided in this paper that the characteristic frequency of the overdamped environment is an extremely crucial factor to regulate the lifetimes of the oscillating signals in 2D electronic spectra and of quantum coherence features of system dynamics. It is worth noting that the proposed scheme benefiting from its stochastic nature and wavefunction framework and many other advantages of substantially reducing the numerical cost, has a great potential to systematically investigate various quantum effects observed in realistic large-scale natural and artificial photosynthetic systems.