Chip-scale transmitter module for real-time continuous-variable QKD

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.