Recently, researchers from Nanjing University and University of Science and Technology of China have completed the first drone-based quantum key distribution (QKD) experiment using a small octocopter. The work is published on Physical Review Letters entitled “Experimental demonstration of drone-based quantum key distribution” (Phys. Rev. Lett. 2024, 133, 200801).
So far, QKD has been demonstrated using fiber or satellite, covering key nodes over large distance up to hundreds or thousands of kilometers. However, the ability of direct quantum connection to end users is still lacking up to date. Flexible mobile nodes, like unmanned vehicles, are capable to establish wireless mobile quantum links for single photon signals, and reach the end users, either in standstill or motion, as required for a mobile quantum network construction. Previously, Zhu’s group in Nanjing University have proposed the original idea of constructing quantum network using mobile platforms like drones and demonstrated the first drone-based entanglement distribution (Natl. Sci. Rev. 2020, 7, 921) and optical-relayed entanglement distribution (Phys. Rev. Lett. 2021, 126, 020503). These experiments prove that high-fidelity photon state distribution is possible, however, a practical quantum task, like QKD, has not reported up to date using drone-based mobile quantum links.
Here, in this work, the researchers made several technology achievements including a compact QKD system, a fully automated and high-precision acquisition, pointing, and tracking system, and a stable-in-motion polarization control system. By loading the above systems on a small homemade octocopter, the researchers have completed quantum key distribution from the flying drone to a ground station successfully, with maximum average secret key rate exceeding 8 kHz and 6 kHz during night and daytime, respectively.
Dr. Xiao-Hui Tian and Ran Yang are co first authors of the paper. Dr. Hua-Ying Liu, Prof. Yan-Xiao Gong and Prof. Zhenda Xie are co corresponding authors of the paper. Prof. Zhen-Qiang Yin, Prof. Shuang Wang, Prof. Wei Chen from the University of Science and Technology of China and Nanzhi Xinlian Technology (Huzhou) Co., Ltd. participate in the work. Prof. Shi-Ning Zhu supervise the whole work. This work was supported by National Natural Science Foundation of China, National Key R&D Program of China, Leading-edge technology Program of Jiangsu Natural Science Foundation, the Excellent Research Program of Nanjing University and Jiangsu Funding Program for Excellent Postdoctoral Talent.