Near optimal single photon sources in the solid state

TL;DR

This paper presents a new quantum dot-based single-photon source that achieves near-unity indistinguishability, high purity, and brightness, surpassing previous technologies and enabling scalable quantum optical applications.

Contribution

The authors demonstrate electrically controlled cavity structures with quantum dots that produce on-demand, ultra-pure, and highly indistinguishable single photons with unprecedented brightness.

Findings

Indistinguishability of 0.9956 with g²(0)=0.0028

Photon extraction efficiency of 65%

Brightness of 0.154, 20 times brighter than comparable sources

Abstract

Single-photons are key elements of many future quantum technologies, be it for the realisation of large-scale quantum communication networks for quantum simulation of chemical and physical processes or for connecting quantum memories in a quantum computer. Scaling quantum technologies will thus require efficient, on-demand, sources of highly indistinguishable single-photons. Semiconductor quantum dots inserted in photonic structures are ultrabright single photon sources, but the photon indistinguishability is limited by charge noise induced by nearby surfaces. The current state of the art for indistinguishability are parametric down conversion single-photon sources, but they intrinsically generate multiphoton events and hence must be operated at very low brightness to maintain high single photon purity. To date, no technology has proven to be capable of providing a source that simultaneously generates near-unity indistinguishability and pure single photons with high brightness. Here, we report on such devices made of quantum dots in electrically controlled cavity structures. We demonstrate on-demand, bright and ultra-pure single photon generation. Application of an electrical bias on deterministically fabricated devices is shown to fully cancel charge noise effects. Under resonant excitation, an indistinguishability of $0.9956\pm0.0045$ is evidenced with a $g^{2}(0)=0.0028\pm0.0012$. The photon extraction of $65%$ and measured brightness of $0.154\pm0.015$ make this source $20$ times brighter than any source of equal quality. This new generation of sources open the way to a new level of complexity and scalability in optical quantum manipulation.