Quantum photonics with solid-state devices
Spontaneous parametric down conversion has served as an excellent workhorse for fundamental test of quantum mechanics, proof-of-principle demonstrations of multi-photon entanglement , quantum teleportation  and optical quantum computing . Yet, its probabilistic nature and higher-‐order photon emission limit the scalability in optical quantum information processing. Self-‐assembled quantum dots (QD) are deterministic single-photon emitters on a solid-state platform with high quantum efficiency and light-matter interface. For quantum information applications, the three most important metrics are the photon purity, indistinguishability, and efficiency. These key properties have been compatibly combined simultaneously on the same QD-micropillar very recently [4,5]. An important next challenge is to extend the single-photon sources to multiple photonic qubits. To this end, by pulsed s-‐shell resonant excitation of a single QD-micropillar, we generate long streams of thousands of single photons with high mutual indistinguishability , which allowed scalable multi-photon Boson sampling experiments with a performance beating the best parametric down-conversion sources.
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