A Fast and Versatile QKD System with Hardware Key Distillation and Wavelength Multiplexing

The QCrypt project, funded by the Nano-Tera program, is gently terminating. QCrypt involves ID Quantique SA in Geneva, the University of Geneva through its Applied Physics Group, the EPFL, through the Telecommunications Circuits Laboratory, the ETH Zürich, through the Integrated Systems Laboratory, and the HES-SO, through two institutes of the HEIG-VD (REDS and IICT) as well as the hepia.

The QCrypt project purpose consisted mainly in building a next-generation quantum key distribution system integrated with a 100 Gb/s layer-2 encryptor relying on classical cryptography.

A first paper has been uploaded to arXiv recently, which discusses the technical aspects of the QKD engine. Co-written with 20 (!) authors, it describes for the first time, to the best of our knowledge, the throughput achievable in practice of (distilled) key bits for a pre-defined security level when taking into account finite-key effects, authentication costs and the composability of keys. Here is the paper’s abstract:

We present a 625 MHz clocked coherent one-way quantum key distribution (QKD) system which continuously distributes secret keys over an optical fibre link. To support high secret key rates, we implemented a fast hardware key distillation engine which allows for key distillation rates up to 4 Mbps in real time. The system employs wavelength multiplexing in order to run over only a single optical fibre and is compactly integrated in 19-inch 2U racks. We optimized the system considering a security analysis that respects finite-key-size effects, authentication costs, and system errors. Using fast gated InGaAs single photon detectors, we reliably distribute secret keys with rates up to 140 kbps and over 25 km of optical fibre, for a security parameter of 4E-9.


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