Research on optical fiber link performed by the group MMT of Laboratoire de physique des lasers (LPL, CNRS/Université Paris 13) and the laboratory Systèmes de référence temps-espace (SYRTE, CNRS/Observatoire de Paris/UPMC, associated to LNE), have just contributed to a new clock measurement with an unprecedented resolution. By linking Paris to Braunschweig (in Germany) with an optical fiber link of 1400 km, the ticking rates of two ultrastable optical clocks, developed at SYRTE and Physikalisch-Technische Bundesanstalt (PTB), and separated by 700 km, were compared. This comparison is 20 times more precise than what was achievable so far using GPS, and the measurement is 10 000 faster for the same resolution. The fractional frequency difference, of 2x10-15, is attributed to an effect of general relativity, which affects clocks at different heights (20 m difference).
The French part of the optical fiber link was established with the support of the French education and research network RENATER. The know-how on the equipment installed on the fiber network is now transmitted to three French companies in the frame of the project REFIMEVE+.
This work has been published in Nature Communications on 9 August 2016.
Read the article on Nature Communication’s website.
Press alert (in French).
Visit REFIMEVE+ website for more details.