Real-time quantum key distribution over an emulated satellite to ground link

Real-time generation of quantum keys between satellite and ground nodes is essential for a scalable and global quantum network. We report the development of a QKD system that operate at gigahertz clock rate with multiplexed classical and quantum channels. This system is tested on a free-space link which is an emulation of the satellite to ground link with dynamic loss and random misalignments. With the assumption of a small satellite in low Earth orbit and a ground station with moderate aperture, we demonstrate the generation of >5 Mbits of quantum keys in a single emulated satellite pass.