Interaction of Rydberg Excitons in Cuprous Oxide with Phonons and Photons: Optical Linewidth and Polariton Effect

TL;DR

This paper investigates how phonon scattering affects the optical linewidth of Rydberg excitons in Cu2O and concludes that polariton effects are negligible for low quantum numbers, clarifying the exciton-photon interaction dynamics.

Contribution

It provides a comprehensive explanation of exciton linewidth broadening due to phonons and clarifies the conditions under which polariton effects become observable in Cu2O.

Findings

Optical linewidth is mainly due to phonon scattering, especially non-polar optical modes.

Polariton effects are only relevant for exciton states with quantum number n>28.

No polariton effects observed in experiments with n≤28.

Abstract

We demonstrate that the optical linewidth of Rydberg excitons in Cu2O can be completely explained by scattering with acoustical and optical phonons, whereby the dominant contributions stems from the non-polar optical modes. The consequences for the observation of polariton effects are discussed. We find that an anti-crossing of photon and exciton dispersions exists only for states with main quantum numbers n>28, so polariton effects do not play any role in the experiments reported up to now.