On-demand solid-state single-photon source with 99.99% purity

摘要

True on-demand high-repetition-rate single-photon sources are highly soughtafter for quantum information processing applications. However, any coherentlydriven two-level quantum system suffers from finite re-excitation processesunder pulsed excitation, limiting the purity of on-demand single-photonemission. Here, we present a solid-state source of on-demand single-photonsyielding a raw multi-photon emission probability of$g^{(2)}(0)=(7.5\pm1.6)\cdot10^{-5}$ without any background subtraction nordata processing. To this date, this is the lowest value of $g^{(2)}(0)$reported for any single-photon source even compared to the previously bestbackground subtracted values. We achieve this result on GaAs/AlGaAs quantumdots embedded in a low-Q planar cavity by employing (i) a two-photon excitationprocess and (ii) a filtering and detection setup featuring two superconductingsingle-photon detectors with ultralow dark-count rates of$(0.01^{+0.02}_{-0.01})\text{Hz}$ and $(0.02^{+0.04}_{-0.02})\text{Hz}$,respectively. Re-excitation processes are dramatically suppressed by (i) ,while (ii) removes false coincidences resulting in a negligibly low noisefloor.