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International Conference on Transparent Optical Networks

BB84 decoy-state QKD protocol over long-distance optical fiber

Giulia Guarda, Domenico Ribezzo, Daniela Salvoni, Ciro Bruscino, Pasquale Ercolano, Mikkel Ejrnaes, L. Parlato, Cai Zhang, Hao Li, Lixing You, Ilaria Vagniluca, Claudia De Lazzari, Tommaso Occhipinti, Giovanni Piero Pepe, Alessandro Zavatta, Davide Bacco

Published Jul 2, 2023• 2 citations

Abstract

Quantum key distribution represents one of the most mature and well-studied advances in quantum technologies. Many protocols have been implemented, breaking record distances both employing satellites [1] and fiber-based systems [2]. However, there still are open challenges in achieving long-distance links without implementing quantum repeaters. One of the main limiting factors comes from the non-ideality of detection systems, in particular from intrinsic dark counts. As the covered distances increase, the signal decreases in intensity and the intrinsic noise in the detector prevails, hindering the extraction of a secret key. In this work, we propose the use of high-performance state-of-the-art superconducting nanowire single-photon detectors (SNSPD) showing ultra-low dark count rates to reduce the quantum bit error rate (QBER) in the detection system. Overall we achieved a link distance of 55 dB equivalent to 275 km in ultra low-loss fiber.

DOI: 10.1109/icton59386.2023.10207397

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