Chip-Based 16 GBaud Continuous-Variable Quantum Key Distribution

TL;DR

This paper presents the first fully integrated chip-based continuous-variable quantum key distribution system operating at 16 GBaud, achieving record secure key rates over fiber links, advancing scalable quantum-secure communication.

Contribution

It introduces the first photonic-integrated CVQKD system with high symbol rate and record key rates, demonstrating practical, scalable quantum communication technology.

Findings

Achieved a secure key rate of 0.289 Gb/s over 20 km fiber.

Operated at a classical telecom symbol rate of 16 GBaud.

Established a new record in key rate for integrated CVQKD systems.

Abstract

Quantum key distribution (QKD) stands as the most successful application of quantum information science, providing information-theoretic security for key exchange. While it has evolved from proof-of-concept experiments to commercial products, widespread adoption requires chip-based integration to reduce costs, enable mass production, facilitate miniaturization, and enhance system performance. Here, we demonstrate the first fully photonic-integrated continuous-variable QKD (CVQKD) system operating at a classical telecom symbol rate of 16 GBaud. Our system integrates a silicon photonic transmitter circuit (excluding the laser source) and a 20 GHz photonic-electronic receiver, which features a phase-diverse silicon photonic integrated circuit and custom-designed GaAs pHEMT transimpedance amplifiers. Advanced digital signal processing allows our system to achieve the highest reported secure key rate to date, reaching 0.289 Gb/s and 0.246 Gb/s over a 20 km fiber link in the asymptotic and finite-size regimes, respectively. These results establish a record key rate and represent a critical step toward scalable, cost-effective, and mass-deployable quantum-secure communication using photonic-integrated CVQKD systems.