Contributed Talk 2a

Abstract: We demonstrate an entanglement-based quantum key distribution (QKD) system employing frequency-bin encoding. The entangled state is generated using two independent high-finesse ring resonators fabricated on a silicon photonic chip. The system implements the BBM92 protocol with a passive basis selection scheme and enables simultaneous acquisition of sixteen projective measurements across two mutually unbiased bases. To counteract random phase fluctuations induced by thermal instabilities in the transmission fiber, we apply a real-time adaptive phase correction to the measurement basis. We achieve stable QKD over a 26 km fiber spool with a secure key rate exceeding 4.5 bit/s.

Abstract: The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and nonrepudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-scale deployment and reconfigurable networking construction. Here, we introduce and verify a chip-based QDS network, placing the complicated and expensive measurement devices in the central relay while each user needs only a low-cost transmitter. We demonstrate the network with a three-node setup using an integrated encoder chip and decoder chip. By developing a 1-decoy-state one-time universal hashing-QDS protocol, we achieve a maximum signature rate of 0.0414 times per second for a 1 Mbit messages over fiber distances up to 200 km, surpassing all current state-of-the-art QDS experiments. This study validates the feasibility of chip-based QDS, paving the way for large-scale deployment and integration with existing fiber infrastructure.