Guo Guangcan's team at CSU makes latest progress in high-security quantum key distribution network
Academician Guo Guangcan's team at the Chinese University of Science and Technology (CSU) has made important progress in quantum key distribution networking research. The team, Prof. Zhengfu Han and his collaborators Shuang Wang, Zhenqiang Yin, and Wei Chen, have realized a non-trusted node quantum key distribution network resistant to environmental interference, which has comprehensively improved the security, availability, and reliability of quantum key distribution networks and taken an important step toward realizing next-generation quantum networks.
The related research results were published online in the internationally renowned academic journal Optica on July 16 [Optica, 9, 812-823(2022)].
Network security is an important theme in the information age, and quantum key distribution networks, based on the principles of quantum physics, can provide information-theoretically secure and confidential communication services for thousands of users and build a secure and controlled network environment. At present, quantum confidential communication networks have been deployed successively around the world, which have proved their superior secure communication capability in practice. However, the demand for trusted nodes in the network has raised the threshold of its practical deployment. How to dispense with the intermediate nodes that must be trusted on the user link and reduce the security requirements on the communication link, so as to build the next-generation quantum network based on untrusted nodes, is an urgent problem now.
The Measurement Device Independent Quantum Key Distribution protocol (MDI-QKD) can build a secure communication link between two users by setting a non-trusted node to jointly measure the encoded quantum states, and is an important player in building a 100-km metropolitan quantum network. However, joint measurement not only limits the number of participating users, but also imposes higher requirements on the stability of the channel environment, which is not conducive to deployment in complex network environments. Han Zhengfu's group has been conducting in-depth research around this problem for many years, and in 2015 realized a double-independent system for reference system measurement devices (Phys. Rev. Lett. 115, 160502 (2015)), which solved the problem of phase perturbation; in 2017 designed an environmentally robust system (Optica 4, 1016-1023 (2017)), which further achieved anti-polarization perturbation capability; and a non-independent networking scheme (Photon. Res. 9, 1881-1891 (2021)) was proposed in 2021 to explore the networking route of measurement device-independent systems. At this point, the conditions are in place to solve the problems of multi-user availability and reliability under environmental disturbances in MDI-QKD networks.
Figure 1 Block diagram of the implementation of the measurement device-independent network
In this study, the group designed a non-phase-sensitive quantum encoder with a "Sagnac-Mach-Zendel" structure, which can eliminate the compensation of the phase reference system; at the same time, the group erased the polarization information of the encoded quantum state by randomization to make it resistant to channel polarization perturbation; finally, the group reused the polarization dimension for Finally, the group reused the polarization dimension for multi-user pairing, which can realize Hong-Ou-Mandel interferometry and joint measurement for multiple users simultaneously. On this basis, the group has completed the construction of a measurement device-independent quantum key distribution network, which is simultaneously resistant to environmental interference, does not require trusted nodes, and supports flexible multi-user networking.
The results promote the practicalization of next-generation quantum confidentiality communication networks and make a useful exploration of the specific shape of the future quantum Internet.
The co-first authors of this work are Yuanguanjie Fan, a special associate researcher at the Key Laboratory of Quantum Information, CAS, and Fengyu Lu, a postdoctoral fellow, and Prof. Shuang Wang and Zhenqiang Yin are the co-corresponding authors of this work. This work was supported by grants from the Ministry of Science and Technology, the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, the Chinese Academy of Sciences, and Anhui Province.
Link to article：
https://doi.org/10.1364/OPTICA.458937
