Juan C. Loredo, Nor A. Zakaria, Niccolo Somaschi, Carlos Anton, Lorenzo de Santis, Valerian Giesz, Thomas Grange, Matthew A. Broome, Olivier Gazzano, Guillaume Coppola, Isabelle Sagnes, Aristide Lemaitre, Alexia Auffeves, Pascale Senellart, Marcelo P. Almeida, and Andrew G. White
The desiderata for an ideal photon source are high brightness, high single-photon purity, and high indistinguishability. Defining brightness at the first collection lens, these properties have been simultaneously demonstrated with solid-state sources; however, absolute source efficiencies remained close to the 1% level and indistinguishability had only been demonstrated for photons emitted consecutively on the few-nanoseconds scale. We demonstrate solid-state single-photon sources with scalable performances. In one device, an absolute brightness at the output of a single-mode fiber of 14% and purities of 97.1%–99.0% are demonstrated. When nonresontantly excited, it emits a long stream of photons that exhibit indistinguishability up to 70%—above the classical limit of 50%—even after 33 consecutively emitted photons with a 400 ns separation between them. Resonant excitation in other devices results in near-optimal indistinguishability values: 96% at short timescales, remaining at 88% in timescales as large as 463 ns after 39 emitted photons. The performance attained by our devices brings solid-state sources into a regime suitable for scalable implementations.
Figure: Temporal-dependent indistinguishability under strictly resonant excitation. Two-photon interference histograms with Device 2 of parallelly polarized photons at (a) Δt=12.2 ns and (b) Δt=158.5 ns, under a pi-pulse preparation. (c) Second-order autocorrelation measurement at pi-pulse. (d) Indistinguishability between a first and n-th consecutive emitted photon for two. Indistinguishability remains robust in the temporal domain, decreasing only by 4.4% in 159 ns or by 8.3% in 463 ns.