True on--demand high--repetition--rate single--photon sources are highly sought after for quantum information processing applications. However, any coherently driven two-level quantum system suffers from a finite re-excitation probability under pulsed excitation, causing undesirable multi--photon emission. Here, we present a solid--state source of on--demand single photons yielding a raw second--order coherence of g(2)(0)=(7.5±1.6)×10−5 without any background subtraction nor data processing. To this date, this is the lowest value of g(2)(0) reported for any single--photon source even compared to the previously best background subtracted values. We achieve this result on GaAs/AlGaAs quantum dots embedded in a low--Q planar cavity by employing (i) a two--photon excitation process and (ii) a filtering and detection setup featuring two superconducting single--photon detectors with ultralow dark-count rates of (0.0056±0.0007)s−1 and (0.017±0.001)s−1, respectively. Re--excitation processes are dramatically suppressed by (i), while (ii) removes false coincidences resulting in a negligibly low noise floor.
@article{arxiv.1712.06937,
title = {On-demand generation of background--free single photons from a solid-state source},
author = {Lucas Schweickert and Klaus D. Jöns and Katharina D. Zeuner and Saimon Filipe Covre da Silva and Huiying Huang and Thomas Lettner and Marcus Reindl and Julien Zichi and Rinaldo Trotta and Armando Rastelli and Val Zwiller},
journal= {arXiv preprint arXiv:1712.06937},
year = {2018}
}