Phase-correlation-free quantum key distribution source operating at gigahertz rates

Article Article scientifique Lettre Phase-correlation-free quantum key distribution source operating at gigahertz rates eng 2026-08-14 2026-08-01 author Kumar Shashank 0009-0008-4315-417X 428330 Serv com physique appliquée (FIGCO) author Marcomini Alessandro 0009-0000-3577-029X author Millet Loïc Henri Fabrice 0000-0002-3224-382X 418885 author Taher Towsif 0000-0002-7358-1665 405346 Serv com physique appliquée (FIGCO) author Cavalié Aurélien 0009-0002-8145-9755 author Houlmann Raphaël 0000-0003-0505-6890 718710 Serv com physique appliquée (FIGCO) author Cabrerizo Pastor David 952348 Serv com physique appliquée (FIGCO) author Boso Gianluca 0009-0007-0578-5790 author Curty Marcos 0000-0002-0330-6828 author Thew Rob 0000-0003-0188-6053 541344 Serv com physique appliquée (FIGCO) author Korzh Boris 0000-0002-8262-9720 782725 Serv com physique appliquée (FIGCO) 081302 10.1063/5.0347954 2378-0967 https://pubs.aip.org/app/article/11/8/081302/3401133/Phase-correlation-free-quantum-key-distribution Phase randomization is essential for the security of practical decoy-state quantum key distribution (QKD) systems. Commonly, implementations rely on laser sources, which are either actively phase-randomized, or gain-switched. However, at high repetition rates, these show correlations, which can ultimately compromise security and performance. We present a 1.25 GHz phase-randomized QKD source based on a super-luminescent light emitting diode (SLED) operating in the C-band as a compact and cost-effective alternative. The source generates ∼100 ps optical pulses with 400 ps pulse-to-pulse separation, compatible with high-speed time-bin encoding. Interferometric measurements demonstrate >99% visibility between adjacent time bins, confirming strong first-order coherence within the same quantum signals, while the spontaneous-emission-driven nature of the SLED drives intrinsic global phase randomization between adjacent signals with a visibility upper bound of the order of 2%. This work establishes a scalable SLED-based platform for high-speed prepare-and-measure QKD systems. Dewey 500.2 European Space AgencyPhi-Lab Switzerland as Part of ESA Phi-LabNET and ESA ScaleUp Program MQ-SoC Swiss State Secretariat for Research and Innovation UeM019-3 Galician Regional Government Spanish Ministry Science, Innovation and Universities Fondo Europeo de Desarrollo Regional PID2024-162270OB-I00 European Commission Quantum-Safe-Internet 101072637 QSI EU HE 35 Groupe de physique appliquée 135 false 1455 Groupe Korzh APL photonics 11 8 32dd5b21-02e7-4c76-9871-b537812105b8 Article (Published version) Public 081302_1_5.03479541.pdf 4504668 application/pdf CC BY-4.0 2c652317a7a99edae9478d463cfd6ea982444323555466f7980d6519834dd2ac openAccess Faculté des sciences / Section de physique / Groupe de physique appliquée

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Kumar, Shashank