Daylight Operation of a High-Speed Free-Space Quantum Key Distribution using Silica-Based Integration Chip and Micro-Optics-Based Module

We developed a high-speed quantum key distribution (QKD) system integrated with a compact self-developed silica-based planar lightwave circuit chip and a micro-optics-based polarization module. Also, we demonstrated that our system can generate average secure keys at the rate of 701.22 kbps over a free-space link of 275 m in daylight by using effective noise filtering systems in the temporal, spectral, and spatial domains. Real-time beam tracking system was adopted to stabilize the fluctuation of the beam position.