Purcell-enhanced single-photon emission from a strain-tunable quantum dot in a cavity-waveguide device

Abstract

On-chip quantum photonics is a promising route toward the implementation of complex photonic architectures on a small footprint. Therefore, different photonic components demonstrated for off-chip operation must be realized in an integrated manner. An essential building block for the realization of this goal is the integration of efficient on-demand single-photon sources within waveguide circuits. Here, we address this challenge by demonstrating the Purcell-enhanced single-photon emission from an In(Ga)As quantum dot coupled to a high-Q cavity-waveguide device. The combination with a piezoelectric actuator further enables the strain-induced emission energy tuning of the quantum dot as well as the cavity mode. We observe wavelength shifts up to 0.85 nm for the quantum dot, with a differential tuning factor of four between emitter and cavity. This allows for the full compensation of the spectral mismatch between a selected quantum dot and the cavity resonance. A nearly twofold enhancement of the spontaneous emission rate is observed at resonance with the on-demand generation of single photons. This demonstration of a strain-tunable emitter in a waveguide-coupled cavity device represents an essential building block for large scale quantum photonic circuits, especially if combined in the future with miniaturization approaches based on recently developed micromachined piezoelectric actuators.