Continuous-Variable Quantum Key Distribution System Design Leveraging Silicon Photonics

Abstract:
Quantum key distribution (QKD) is a technique based on sharing random encryption keys between the transmitter and receiver nodes. QKD guarantees information-theoretically secure key exchange, ensured by the Heisenberg uncertainty principle of quantum mechanics. However, the wide-scale adoption and commercial viability of such systems has remained as a challenge. Implementing the QKD scheme in a silicon photonics chip can solve the problem by enabling compact, low-cost, and energy-efficient transceivers that ensure unconditional communication security. For this purpose, continuousvariable (CV)-QKD systems are particularly well-suited, since such systems work based on the homodyne detection scheme, eliminating the need for single-photon detectors, which suffer from integration challenges. Here, we present our efforts to design a CV-QKD system in silicon photonics technology. The configuration of the CV-QKD transceiver chip is described. On the transmitter side, sequential amplitude and phase modulators are used to modulate the optical signal’s quadratures, and a homodyne detector is used on the receiver side to detect the information. Modulators are realized using the free-carrier plasma dispersion effect. Moreover, specifications of the FPGA and the quantum security gateway demonstrator (QSGD) in the planned demonstrator are described. Finally, the CV-QKD network architecture, including the data plane, control plane, and management plane are described.