Vacuum Rabi spectra of a single quantum emitter

TL;DR

This paper demonstrates the direct observation of vacuum Rabi splitting in a single quantum emitter through its spontaneous emission, revealing new insights into cavity quantum electrodynamics phenomena.

Contribution

It presents the first direct measurement of vacuum Rabi spectra from an emitter’s spontaneous emission, using a novel detection scheme with a quantum dot in a photonic crystal nanocavity.

Findings

Clear vacuum Rabi splitting observed in spontaneous emission

Asymmetric spectra caused by interference effects

Method enables access to emitter-specific cavity QED phenomena

Abstract

We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.