A Pure and Indistinguishable Single‐Photon Source at Telecommunication Wavelength

On-demand single-photon sources emitting pure and indistinguishable photons at the telecommunication wavelength are critical assets toward deployment of fiber-based quantum networks. Indeed, single may serve as flying qubits, allowing communication information over long distances. Self-assembled InAs dots embedded in GaAs constitute an excellent nearly deterministic source high-quality photons, but vast majority operate 900–950 nm range, precluding their adoption a network. A frequency conversion scheme is presented here for converting from to C band, around 1550 nm, achieving 40.8% end-to-end efficiency, while maintaining both high purity degree indistinguishability during with measured values g ( 2 ) 0 = 2.4 % $g^{(2)}(0)=2.4\%$ V (corr) 94.8 $V^{\mbox{(corr)}}=94.8\%$ , respectively.