Indistinguishable single photons from a quantum dot in a nanopost cavity

Abstract

Wavelength-tunable sources of single photons are key devices for scaling up optical quantum technologies. In this context, individual quantum dots (QDs) embedded in broadband photonic nanostructures are particularly appealing. The nanopost cavity, which is built with a segment of photonic wire, offers a rare combination of pronounced Purcell effect, large extraction efficiency, and wide operational bandwidth. So far, however, the on-demand emission of indistinguishable photons, a crucial feature for most envisioned applications, has not been reported with such devices. Here, we implement a quasi-resonant pulsed excitation of a single QD embedded in a nanopost cavity using a phonon-assisted scheme. Intensity correlation measurements then yield an excellent single-photon purity, with g(2)(0) as low as 2.3%. Furthermore, we demonstrate Hong–Ou–Mandel quantum interference between consecutive photons, with a wavepacket overlap reaching 46%. These results mark an important milestone in the development of quantum light sources based on broadband nanopost cavities.