Quantum two-way time transfer over a hybrid free-space and fiber link
Xiao Xiang, Bingke Shi, Runai Quan, Yuting Liu, Zhiguang Xia, Huibo Hong, Tao Liu, Jincai Wu, Qiang Jia, Jianjun Jia, Shougang Zhang, Ruifang Dong
Abstract
Abstract As the superiority of quantum two-way time transfer (Q-TWTT) has been proved convincingly over fiber links, its implementation on free-space links becomes an urgent need for remote time transfer expanding to the transcontinental distance. In this paper, the first Q-TWTT experimental demonstration over a hybrid link of 2 km-long turbulent free-space and 7 km-long field fiber is reported. Despite the significant loss of ∼30 dB and atmospheric turbulence, reliable time transfer performance lasting for overnights has been realized with time stability in terms of time deviation far below 1 picosecond. This achievement shows the good feasibility of quantum-enhanced time transfer in the space-ground integrated optical links and nicely certifies the capability of Q-TWTT in comparing and synchronizing the state-of-the-art space microwave atomic clocks.