From a national to a European Time & Frequency network: from REFIMEVE to FOREST - Christian Chardonnet (LPL, Paris)

In the last six decades, scientific and technological breakthroughs led to an improvement by six orders of magnitude of the relative accuracy of atomic clocks which reaches today 10-18. At that level, the international clock comparisons cannot be performed by GNSS (GPS, Galileo…) methods. By contrast, it has been proven that stabilized optical fiber networks do not degrade the performance of clock comparison even with links larger than 1000 km with a marginal uncertainty of 10-19-10-20. Thanks to these performances, the French network REFIMEVE based on the RENATER backbone delivers the T&F signals coming from the LTE at Paris Observatory to about 30 labs including CERN, with a local node at UGA campus in LIPhy. In Europe several countries develop also similar networks based on the distribution of the T&F signals coming from their own NMI (National Metrological Institute). The FOREST project of a European Research Infrastructure will permit the interconnection of the national networks which will have a major impact for the European metrology. Beyond that, the scientific and technological impact is very broad: it concerns any experiment requiring high precision measurements in fundamental physics, high energy physics, astrophysics, geoscience but also in the domains of quantum communication and of fiber sensing. The talk will give an overview of these recent developments, their impacts, and the challenges still to be met.

Contact: Yann Le Coq