Lorenzo Castelvero

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.