Matthieu Legré

We experimentally implement a quantum coin flipping protocol that guarantees a strictly better security than classically possible against an all powerful adversary over a distance suitable for communication in metropolitan area networks. The implementation is based on a practical plug’n'play system, originally designed for quantum key distribution. Furthermore, we show that our protocol can be combined with quantum coin flipping protocols that provide almost perfect security against adversaries with limited resources and hence enhance them with a level of unconditional security. Our results offer a powerful theoretical and experimental toolbox for future secure quantum communications.

We present the results of the project QCRYPT, a collaborate effort of eight research teams in Switzerland with the ambition to produce a complete and practical fiber based QKD and high speed encryption system. For the QKD part, we put the emphasis on continuous operation with a wavelength multiplexed service channel for synchronization and distillation, efficient hardware real-time distillation, finite key security analysis and frugal authentication. For the secure high-speed encryption of large data volumes, we present a system able to multiplex up to ten 10 Gbit/s Ethernet inputs, pass the 100 Gbit/s data stream through authenticated encryption before transmitting it over an optical fiber to the decryptor. The cipher cores apply and frequently refresh the quantum keys delivered by the QKD system.