Polaritonic Huang-Rhys Factor: Basic Concepts and Quantifying Light-Matter Interaction in Medium

TL;DR

This paper introduces the polaritonic Huang-Rhys factor to quantify light-matter interactions in media, linking electron-phonon coupling concepts to polaritonic phenomena and providing a parameter-free evaluation framework.

Contribution

It presents a new polaritonic HR factor that captures light-matter coupling effects, including dipole interactions and self-energy, in arbitrary dielectric environments.

Findings

Good agreement with experimental results

Large polaritonic HR factors lead to decoupling and multipolariton formation

Framework enables parameter-free evaluation of light-matter interactions

Abstract

Huang-Rhys (HR) factor, a dimensionless factor that characterizes electron-phonon coupling, has been extensively employed to investigate material properties in various fields. In the same spirit, we present a quantity called polaritonic HR factor to quantitatively describe the effects of (i) light-matter coupling induced by permanent dipoles and (ii) dipole self-energy. The former can be viewed as polaritonic displacements, while the latter is associated with the electronic coupling shift. In the framework of macroscopic quantum electrodynamics, the polaritonic HR factor, coupling shift, and modified light-matter coupling strength in an arbitrary dielectric environment can be evaluated without free parameters, whose magnitudes are in good agreement with the previous experimental results. In addition, polaritonic progression developed in our theory indicates that large polaritonic HR factors can result in light-matter decoupling, multipolariton formation, and non-radiative transition. We believe that this study provides a useful perspective to understand and quantify light-matter interaction in medium.