High precision synchronization of time and frequency and its applications

We discuss the concept and methods for remote synchronization of time and frequency.We discuss a recent experiment that demonstrated time and frequency synchronization via a commercial fiber network, reaching accuracy of 7×10^－15/s, 5×10^－19/day, and a maximum time uncertainty of less than 50 femtoseconds. We discuss synchronization methods applicable to different topologies and their important scientific applications.