Quantum Key Distribution With an Integrated Photonic Receiver

Photonic integrated circuits (PICs) are key in advancing quantum technologies for secure communications. They offer inherent stability, low losses and compactness compared to standard fiber-based and free-space systems. Our reasearch demonstrates PIC's effectivness in enhancing quantum communications, implementing a three-state BB84 protocol with decoy-state method. We employ an integrated receiver and superconducting nanowire single photon detectors (SNSPDs) to achieve technological advancements. One of the most notable results is the extraction of a secret key over a record-breaking 45 dB channel attenuation. Our results demonstrate a remarkable 220% boost in key rate compared to our prototype fiber-based receiver over a 10 dB channel attenuation. This improvement in the secret key rate (SKR) signifies the potential of integrated photonics to advance the field of quantum communication.