Low Bit Error Rate Quantum Key Distribution Based on Integrated Silicon Photonics

Quantum communication has extremely high security and is the development direction of future communication networks. In this paper, an on-chip path, off-chip polarization encoded quantum key distribution chip is designed and fabricated using advanced silicon photonics fabrication technology. Using a special two-dimensional grating, we can convert light of different path states into corresponding polarization states and propagate in free space. The performance of the basic optics, waveguides, gratings, and Mach-Zehnder interferometers on the chip is tested. In the demonstrated quantum key distribution experiment, the quantum bit error rate is as low as 1.08%. It lays the foundation for the future development of advanced integrated quantum information.