On-Demand Generation of Indistinguishable Photons in the Telecom C-Band Using Quantum Dot Devices

Vajner DA; Holewa P; Zięba-Ostój E; Wasiluk M; Helversen M; Sakanas A; Huck A; Yvind K; Gregersen N; Musiał A; Syperek M; Semenova E; Heindel T

Abstract

Semiconductor quantum dots (QDs) enable the generation of single and entangled photons, which are useful for various applications in photonic quantum technologies. Specifically for quantum communication via fiber-optical networks, operation in the telecom C-band centered around 1550 nm is ideal. The direct generation of QD-photons in this spectral range with high quantum-optical quality, however, remained challenging. Here, we demonstrate the coherent on-demand generation of indistinguishable photons in the telecom C-band from single QD devices consisting of InAs/InP QD-mesa structures heterogeneously integrated with a metallic reflector on a silicon wafer. Using pulsed two-photon resonant excitation of the biexciton–exciton radiative cascade, we observe Rabi rotations up to pulse areas of 4π and a high single-photon purity in terms of g(2)(0) = 0.005(1) and 0.015(1) for exciton and biexciton photons, respectively. Applying two independent experimental methods, based on fitting Rabi rotations in the emission intensity and performing photon cross-correlation measurements, we consistently obtain preparation fidelities at the π-pulse exceeding 80\%. Finally, performing Hong–Ou–Mandel-type two-photon interference experiments, we obtain a photon-indistinguishability of the full photon wave packet of up to 35(3)\%, representing a significant advancement in the photon-indistinguishability of single photons emitted directly in the telecom C-band.