Jigang Ren

Micius satellite was successfully launched into orbit in 2016. In the past three years, we have implemented a series of experimental works, including satellite-to-ground quantum key distribution, quantum entanglement distribution over 1000 km, ground-to-satellite quantum teleportation. The feasibility of a global quantum network has been demonstrated with ground quantum communication networks with optical fiber. In this report, we will present recent works based on Micius satellite, such as: space quantum key distribution and its application, quantum experiment based on quantum entanglement distribution, and expanded application of space quantum communication. The ongoing project in China of high orbit quantum satellite will also be introduced with results of several tests in ground.

Quantum key distribution (QKD) based on the fundamental laws of quantum physics can allow the distribution of secure keys between distant users. However, the imperfections in realistic devices may lead to potential security risks, which must be accurately characterized and considered in practical security analysis. High-speed optical modulators, being as one of the core components of practical QKD systems, can be used to prepare the required quantum states. Here, we find that optical modulators based on LiNbO3, including phase modulators and intensity modulators, are vulnerable to photorefractive effect caused by external light injection. By changing the power of external light, eavesdroppers can control the intensities of the prepared states, posing a potential threat to the security of QKD. We have experimentally demonstrated the influence of light injection on LiNbO3-based optical modulators and analyzed the security risks caused by the potential green light injection attack, along with the corresponding countermeasures.