An academic-industrial team in Japan has connected three laboratories in a 100-kilometer region with an optical telecommunications fiber network stable enough to remotely interrogate optical atomic clocks. This type of fiber link is poised to expand the use of these extremely precise timekeepers by creating an infrastructure that could be used in a wide range of applications such as communication and navigation systems.

Original source: https://www.sciencedaily.com/releases/2020/03/200317130720.htm