Quantum key distribution with a borosilicate-glass-matrix integrated photonic receiver

Photonic integrated circuits (PICs) are key to advancing quantum technologies for secure communications. They offer inherent stability, low losses, and compactness compared to standard fiber-based and free-space systems. Our research demonstrates PICs' effectiveness in enhancing quantum communications; we implement a three-state BB84 protocol with a decoy-state method, and we employ an integrated receiver and superconducting nanowire single-photon detectors to achieve technological advancements. One of the most notable results is the extraction of a secret key over a 45 dB channel attenuation. This achievement in the maximum covered distance signifies the potential of integrated photonics to advance the field of quantum communication.