One-dimensional ZnO exciton polaritons with negligible thermal broadening at room temperature

TL;DR

This paper demonstrates that in ZnO microwires, strong exciton-photon coupling creates one-dimensional exciton polaritons with negligible thermal broadening at room temperature, overcoming phonon dephasing limitations.

Contribution

It reveals that large Rabi splitting in ZnO microwires decouples excitons from phonons, enabling stable polariton modes at room temperature.

Findings

Rabi splitting up to 300 meV observed

Polariton modes with 75% excitonic fraction show no thermal broadening at room temperature

Strong exciton-photon coupling suppresses phonon-induced dephasing

Abstract

Phonon damping is the main source of pure dephasing in the solid state, limiting many fundamental quantum effects to low temperature observations. Here we show how excitons in semiconductors can be totally decoupled from the phonon bath, even at room temperature, thanks to their strong interaction with photons. To do so, we investigated ZnO microwires, a new semiconductor nanostructure made of large band-gap material where the light can be trapped and guided into whispering gallery modes. In this system, the very large coupling regime between exciton and photon results in unusual exciton-polariton of one-dimensional character and Rabi splitting as large as 300meV. We find that polariton modes of excitonic fraction up to 75% exhibit no thermal broadening up to room temperature. We show that this remarkable behavior is due to the very large Rabi splitting as compared to the LO phonon energy.