Giant photoelasticity of polaritons for detection of coherent phonons in a superlattice with quantum sensitivity

TL;DR

This paper demonstrates a giant photoelastic effect in exciton-polaritons within a superlattice, enabling highly sensitive detection of 42 GHz coherent phonons through photon interactions.

Contribution

It reports the discovery of giant photoelasticity of exciton-polaritons and utilizes it for detecting high-frequency phonons with unprecedented sensitivity.

Findings

Detection of 42 GHz phonons with high sensitivity

Giant photoelasticity of exciton-polaritons in superlattices

Enhanced photon-phonon interaction via polaritons

Abstract

The functionality of phonon-based quantum devices largely depends on the efficiency of interaction of phonons with other excitations. For phonon frequencies above 20 GHz, generation and detection of the phonon quanta can be monitored through photons. The photon-phonon interaction can be enormously strengthened by involving an intermediate resonant quasiparticle, e.g. an exciton, with which a photon forms a polariton. In this work, we discover a giant photoelasticity of exciton-polaritons in a short-period superlattice and exploit it for detecting propagating acoustic phonons. We demonstrate that 42 GHz coherent phonons can be detected with extremely high sensitivity in the time domain Brillouin oscillations by probing with photons in the spectral vicinity of the polariton resonance.