Single photon sources based on semiconductor quantum dots offer distinct advantages for quantum information, including a scalable solid-state platform, ultrabrightness, and interconnectivity with matter qubits. A key prerequisite for their use in optical quantum computing and solid-state networks is a high level of efficiency and indistinguishability. Pulsed resonance fluorescence (RF) has been anticipated as the optimum condition for the deterministic generation of high-quality photons with vanishing effects of dephasing. Here, we generate pulsed RF single photons on demand from a single, microcavity-embedded quantum dot under s-shell excitation with 3-ps laser pulses. The pi-pulse excited RF photons have less than 0.3% background contributions and a vanishing two-photon emission probability. Non-postselective Hong-Ou-Mandel interference between two successively emitted photons is observed with a visibility of 0.97(2), comparable to trapped atoms and ions. Two single photons are further used to implement a high-fidelity quantum controlled-NOT gate.
@article{arxiv.1303.4058,
title = {On-demand semiconductor single-photon source with near-unity indistinguishability},
author = {Yu-Ming He and Yu He and Yu-Jia Wei and Dian Wu and Mete Atatüre and Christian Schneider and Sven Höfling and Martin Kamp and Chao-Yang Lu and Jian-Wei Pan},
journal= {arXiv preprint arXiv:1303.4058},
year = {2015}
}