Collective conical intersections through light-matter coupling in a cavity

TL;DR

This paper theoretically investigates how collective conical intersections emerge in a molecular ensemble coupled to a cavity, revealing their dependence on the number of molecules and their role in ultrafast relaxation processes.

Contribution

It demonstrates the existence of collective conical intersections in light-matter coupled systems and links them to the Jahn-Teller effect, advancing understanding of cavity-induced molecular dynamics.

Findings

Non-radiative relaxation rate depends on the number of molecules.

Collective conical intersections appear for N>2 molecules.

These intersections influence ultrafast decay from the upper polariton.

Abstract

The ultrafast non-radiative relaxation of a molecular ensemble coupled to a cavity mode is considered theoretically and by real-time quantum dynamics. For equal coupling strength of single molecules to the cavity mode, the non-radiative relaxation rate from the upper to the lower polariton states is found to strongly depend on the number of coupled molecules. For N>2 molecules, the N-1 dark light-matter states between the two optically active polaritons feature true collective conical intersection crossings, whose location depends on the internal atomic coordinates of each molecule in the ensemble, and which contribute to the ultrafast non-radiative decay from the upper polariton. At least N=3 coupled molecules are necessary for cavity-induced collective conical intersections to exist and, for identical molecules, they constitute a special case of the Jahn-Teller effect.