# Collective Rayleigh Scattering from Molecular Ensembles under Strong Coupling

## TL;DR

This study investigates how molecules in an optical cavity under strong coupling produce collective Rayleigh scattering via cavity polaritons, revealing high scattering efficiency and delocalized wavefunctions.

## Contribution

It provides the first spectroscopic evidence of collective Rayleigh scattering from molecular ensembles under strong coupling, highlighting the role of cavity polaritons.

## Key findings

- Polaritonic states exhibit up to 25% Rayleigh scattering efficiency.
- Scattering is collective and involves a large ensemble of molecules.
- Wavefunctions are delocalized across the molecular ensemble.

## Abstract

Rayleigh scattering is usually considered to be the elastic scattering of photons from sub-wavelength physical objects, such as small particles or molecules. Here, we present the spectroscopic study of the scattering properties of molecules embedded in an optical cavity under strong coupling conditions, where the collective interaction between the molecules and the cavity gives rise to composite light-matter excitations known as cavity polaritons. We show that the polaritonic states exhibit strong resonant Rayleigh scattering, reaching 25% efficiency. Since the polaritonic wavefunctions in such systems are delocalized, our observations correspond to the collective scattering of each photon from a large ensemble of molecules.