Major breakthrough! Mozi satellite realizes quantum safe time transfer for the first time


Recently, pan Jianwei's team of University of science and technology of China used Mozi quantum science experimental satellite to realize the principle experiment verification of quantum safe time transfer for the first time in the world, which laid a foundation for building a safe and high-precision satellite navigation system in the future. The results were published online on May 11, 2020 in the internationally renowned academic journal Nature Physics.

Model of Mozi quantum communication satellite

Time synchronization is the core technology of navigation, positioning and other applications in daily life. At present, time synchronization technology is widely used, including satellite navigation and positioning system time synchronization, optical fiber network time synchronization and so on. In recent years, the security of time synchronization has been widely concerned. All kinds of network systems, such as computer network, financial exchange market, power and energy network, need a unified time benchmark. If these systems suffer from malicious attacks, the time errors caused by them will lead to network crashes, navigation and positioning errors and other major security accidents. However, the widely used time synchronous transmission technology is facing the potential risks of data tampering, signal deception and other attacks.

Quantum communication technology brings new solutions to secure time synchronization. Based on the principle of quantum non cloning, time transfer technology based on single photon quantum state can fundamentally ensure the security of signal transmission process. Pan Jianwei's team first proposed a quantum secure time synchronization scheme based on two-way free space quantum key distribution technology. In this scheme, the single photon quantum state is used as the signal carrier of time transfer and key distribution to synchronize time and generate key. The key generated in this process is used to encrypt the classical time data, so as to ensure the safe transmission of time data.

Not only that, pan Jianwei's team has broken through the key technical problems such as single photon time transfer between satellite and ground, high-speed two-way asynchronous laser time transponder between satellite and ground, realized the technical verification of quantum time synchronization between satellite and ground, obtained the satellite ground time transfer accuracy of up to 30ps, and reached the international advanced level of satellite ground laser time transfer.

This research achievement has far-reaching influence. It not only greatly promotes the research and application of quantum precision measurement related fields, but also lays the foundation for building a safe satellite navigation system in the future. It has made a significant breakthrough in the safety and synchronization accuracy of satellite time synchronization, which is not expected to be applied in time-frequency related fields.