Continuous-variable quantum key distribution (CV-QKD) enables secure communication over standard telecom infrastructure, but scaling is stalled by bulky, discrete optical hardware. We address this bottleneck by demonstrating a real-time CV-QKD system driven by a chip-scale hybrid transmitter using commercial telecom components. Combining a micro-optic external-cavity laser with a monolithic photonic integrated IQ modulator we enable secure secret-key generation over 102 km of optical fiber while reducing optical volume by 95% relative to the commercial discrete-component counterpart. Moreover, real-time operation overcomes offline post-processing bottlenecks of experimental setups. This work bridges laboratory demonstrations and field-deployable technology for cost-effective quantum networks.
Continuous-variable quantum key distribution (CV-QKD) enables secure communication over standard telecom infrastructure, but scaling is stalled by bulky, discrete optical hardware. We address this bottleneck by demonstrating a real-time CV-QKD system driven by a chip-scale hybrid transmitter using commercial telecom components. Combining a micro-optic external-cavity laser with a monolithic photonic integrated IQ modulator we enable secure secret-key generation over 102 km of optical fiber while reducing optical volume by 95% relative to the commercial discrete-component counterpart. Moreover, real-time operation overcomes offline post-processing bottlenecks of experimental setups. This work bridges laboratory demonstrations and field-deployable technology for cost-effective quantum networks.
Continuous-variable quantum key distribution (CV-QKD) enables secure communication over standard telecom infrastructure, but scaling is stalled by bulky, discrete optical hardware. We address this bottleneck by demonstrating a real-time CV-QKD system driven by a chip-scale hybrid transmitter using commercial telecom components. Combining a micro-optic external-cavity laser with a monolithic photonic integrated IQ modulator, we enable secure secret-key generation over 102 km of optical fiber while reducing optical volume by 95% relative to the commercial discrete-component counterpart. Moreover, real-time operation overcomes the offline post-processing bottlenecks of experimental setups. This work bridges laboratory demonstrations and field-deployable technology for cost-effective quantum networks.
Quantum key distribution (QKD) is the fastest-growing and relatively mature technology in the field of quantum information, enabling information-theoretically secure key distribution between two remote users. Although QKD based on off-the-shelf telecom components has been validated in both laboratory and field tests, its high cost and large volume remain major obstacles to large-scale deployment. Photonic integration, featured by its compact size and low cost, offers an effective approach to addressing the above challenges faced by QKD. Here, we implement a high-performance, integrated local local oscillator continuous-variable (CV) QKD system based on an integrated silicon photonic transmitter and receiver. By employing a high-speed silicon photonic integrated in-phase and quadrature modulator, a low-noise and high-bandwidth silicon photonic integrated heterodyne detector, and digital signal processing, our CV-QKD system achieves a symbol rate of up to 1.5625 GBaud. Furthermore, the system achieves asymptotic secret key rates of 31.05 and 5.05 Mbps over 25.8 and 50.4 km standard single-mode fiber, respectively, using 8-phase-shift keying discrete modulation. Our integrated CV-QKD system with a high symbol rate and long transmission distance paves the way for the quantum secure communication network in metropolitan areas.
Quantum key distribution (QKD) is a quantum communication technology that offers absolute security. Among its various implementations, continuous-variable (CV) QKD has garnered significant attention due to its high secret key generation rates and compatibility with conventional optical telecommunication infrastructure, which operates under ambient conditions. However, chip-based integration is crucial for realizing practical and scalable CV-QKD networks, and photonic integrated circuit technology is a potential solution, leveraging the on-chip integration of essential optical components onto silicon photonic circuits. Therefore, this work presents a compact, stable, and cost-effective quantum photonic CV-QKD system on a chip. Our architecture combines time- and polarization-multiplexing with high-extinction-ratio pulse generation to mitigate excess noise. At the same time, a real-time feedback control mechanism compensates for polarization drift, ensuring robust system performance. Fiber-based evaluations reveal secret key generation rates of 2.55 Mbps over 25 km and 0.737 Mbps over 50 km with 12 h stable operation, establishing, to our knowledge, a new benchmark for integrated photonic CV-QKD systems with both the transmitter and receiver on-chip. These results mark a significant milestone in on-chip quantum communication, paving the way for widespread adoption of photonic integrated circuits in future metropolitan quantum-secure networks.
We demonstrate the first fully integrated continuous-variable quantum key distribution (CV-QKD) transmitter, combining a narrow-linewidth laser, high-speed IQ modulator, and variable optical attenuator on a single indium phosphide (InP) chip. The transmitter occupies a compact footprint of 2 mm by 4.6 mm. Component characterization confirms single-mode laser operation with 120 kHz linewidth, >8 GHz modulator bandwidths, and 58 dB attenuation range. Deployed in a complete heterodyne CV-QKD system with probabilistically shaped 64-QAM, the system achieves an average excess noise of 0.1 shot noise units (SNU) and a secret key rate of 8.4 Mbit/s over a 14.3 km fiber link in the asymptotic regime. These results establish a practical and scalable route toward fully integrated quantum-secure communication systems.
We demonstrate the first fully integrated continuous-variable quantum key distribution (CV-QKD) transmitter, combining a narrow-linewidth laser, high-speed IQ modulator, and variable optical attenuator on a single indium phosphide (InP) chip. The transmitter occupies a compact footprint of 2 mm by 4.6 mm. Component characterization confirms single-mode laser operation with 120 kHz linewidth, >8 GHz modulator bandwidths, and 58 dB attenuation range. Deployed in a complete heterodyne CV-QKD system with probabilistically shaped 64-QAM, the system achieves an average excess noise of 0.1 shot noise units (SNU) and a secret key rate of 8.4 Mbit/s over a 14.3 km fiber link in the asymptotic regime. These results establish a practical and scalable route toward fully integrated quantum-secure communication systems.
Continuous-variable quantum key distribution (CVQKD) is a promising technology for enabling quantum-secure networks, valued for its compatibility with conventional telecommunication hardware and maturing security proofs. Although the need for quantum-safe infrastructure is driven by the threat of advancing quantum computing, the widespread deployment of QKD remains elusive because current discrete-component solutions suffer from high cost, high energy consumption, and lack of conformity with the existing telecom network infrastructure. In this work, we demonstrate a compact CV-QKD system based on a custom-designed, monolithically integrated silicon photonic dualpolarization transceiver, operated with an off-chip seed laser. Taking into account the block length of 2 × 107 and employing 64-quadrature amplitude modulation (QAM) shaped probabilistically, our system achieves a secret key rate of 1.9 Mbit/s in 25km of standard single-mode fiber. This work highlights the significant potential of electronic-photonic integration to advance the practical deployment of QKD networks.