Polarization-Based Quantum Key Distribution Encoder and Decoder on Silicon Photonics

Private and secure communication is an indispensable part of the government and individual activities. With the ever-evolving large-scale of quantum computing, traditional public-key cryptography is severely threatened since its security only relies on the computational complexity of certain mathematical functions. Quantum key distribution (QKD), ascribed to its security based on the inviolability of physics laws, provides an absolutely information-secure solution for the future extensive communication encrypting. Herein this Letter, we proposed a simplified and reconfigurable silicon photonics encoder using a pass-block architecture and experimentally demonstrated its performance with a specialized silicon photonics decoder for high-speed quantum key distribution in polarization-based decoy-state BB84 protocol. We achieved an estimated asymptotic secret key rate of 868 kbps with measured quantum bit error rate (QBER) of 0.90% (Z base) and 1.34% (X base) over 20 km emulated fiber link. This work further advances the process of applying QKD using silicon photonics devices into the future secure telecommunication network.