Influence of strong molecular vibrations on decoherence of molecular polaritons

TL;DR

This paper investigates how strong molecular vibrations influence the decoherence and energy shifts of molecular polaritons in a cavity, revealing multi-phonon effects that alter their spectral properties.

Contribution

The study introduces a variational polaron master equation approach to quantify vibrational effects on polariton decoherence and energy shifts, highlighting multi-phonon dominance in strong coupling regimes.

Findings

Multi-phonon processes dominate transition and dephasing rates.

Vibrational Lamb shifts significantly modify polariton energies.

Spectral line widths depend on the number of molecules in the cavity.

Abstract

We derive the transition rates, dephasing rates, and Lamb shifts for a system consisting of many molecules collectively coupled to a resonant cavity mode. Using a variational polaron master equation, we show that strong vibrational interactions inherent to molecules give rise to multi phonon processes and suppress the light--matter coupling. In the strong light--matter coupling limit, multi-phonon contributions to the transition and dephasing rates strongly dominate over single phonon contributions for typical molecular parameters. This leads to novel dependencies of the rates and spectral line widths on the number of molecules in the cavity. We also find that vibrational Lamb shifts can substantially modify the polariton energies in the strong light--matter coupling limit.