Semiclassical Truncated-Wigner-Approximation Theory of Molecular Exciton-Polariton Dynamics in Optical Cavities

TL;DR

This paper develops a semiclassical truncated Wigner approximation (TWA) theory to model molecular exciton-polariton dynamics, capturing collective behaviors and vibronic effects, with results aligning well with quantum simulations for large molecular ensembles.

Contribution

It extends the TWA framework to include quantum coherence and vibronic coupling in molecular exciton-polariton systems, offering a new semiclassical approach for these complex dynamics.

Findings

TWA results agree with quantum simulations for large systems

Inclusion of vibronic coupling reveals polaron decoupling effects

Semiclassical approach efficiently models collective molecular behaviors

Abstract

Molecular exciton polaritons are hybrid states resulting from the strong coupling of molecular electronic excitations with an optical cavity mode, presenting a promising approach for controlling photophysical and photochemical properties in molecular systems. In this study, we develop a semiclassical theory for molecular exciton-polariton dynamics using the truncated Wigner approximation (TWA) to explore the collective behavior of molecular electronic excited states under strong light-matter coupling. Our approach expands the previously developed TWA theory for molecular vibration-polariton dynamics (J. Chem. Theory Comput. 2024, 20, 3019--3027) by incorporating semiclassical treatment of quantum coherence between ground and excited molecular states. We initially apply the TWA theory to a simplified system of molecules modeled as two-level (spin-1/2) systems, omitting vibronic coupling. The semiclassical results derived from applying the TWA to single-spin operators demonstrate excellent agreement with full quantum dynamic simulations in systems with a sufficiently large number of molecules. Lastly, the TWA theory is extended to incorporate molecular vibronic coupling, revealing the dynamic polaron decoupling effect, where quantum coherence between molecular excitations is preserved under strong light-matter coupling.