Valerio Pruneri

We present a simple polarization transmitter designed to implement protocols from the BB84 + decoy-state family. Operating at a repetition rate of 615 MHz, the transmitter demonstrates low intrinsic quantum bit error rates over several hours of measurements. It is based on self-stable structures for both polarization and intensity modulation, ensuring robust and easy operation. Here, we provide a characterization of the transmitter and some preliminary results obtained from transmitting quantum states over a 50 km deployed fiber link.

We feature the interplay of classical cryptography and quantum technologies, highlighting the importance of the coexistence of both paradigms in practical quantum-safe networks. We motivate the use of QRNGs in PQC protocols, showing that they can potentially increase the security of the system without affecting the performance. We continue proposing some guidelines on the alternatives for QKD authentication methods depending on the use case, the available resources, and the security needs, to improve the practicality of QKD deployment in PKI networks. Moreover, we present a novel authentication scheme for QKD, designed to reduce the key drain from the authentication, showing the results of its implementation in an experimental QKD prepare-measurement BB84 protocol with polarization encoding and decoy states.