The REFIMEVE+ project

The french Equipex project REFIMEVE+ (or MEFINEV+ for Metrological Fiber Network with European Vocation+) is based on a scientific innovation, the ability to transfer an ultra-stable optical frequency on Internet over long-distances without any traffic disruption. Initially from 2012 to 2020, the project has been extended up to 2024.

Currently the transfer frequency faces the difficulty of transporting information without degradation when clocks are separated by hundreds or even thousands of kilometers. This can be made if one of the clocks is transportable, but this solution is mostly not flexible and hard to organize. Otherwise, they are made through one or more satellites of the GPS (Global Positioning System) or telecommunication satellites. 

Despite their high level of maturity, performances of such comparisons are currently limited to a near 10^-15 level in relative terms. Those performances are insufficient to compare the best atomic standards and moreover, they are hardly perfectible as performances are limited by changes introduced in signals by crossing the atmosphere.

GPS: Global Positioning System credit iStockphoto

The French teams of LPL and SYRTE showed that the clock signal transmitted on RENATER’s network between Villetaneuse and Reims (roundtrip: 540km) had an exceptional uncertainty of 2x10^-19 which is equivalent of 0.1s in the relation to the age of the universe! This requires creating a noise correction system inserted in the link while the signal is propagating over the optical fiber.

Allan deviation representing the quality of the transfer rate over the internet link RENATER Villetaneuse-Reims-Villetaneuse: 540 km. In margin, we compared with the GPS transfer and precision of the best clocks in the world. During this experience, the internet traffic data was provided without any disruption.

This system will give us the possibility to compare the ground clocks all across the continent and whose relative accuracy reaches some 10^-16 and 10^-17 soon.

REFIMEVE+ Network

This project is to generalize this concept through close collaboration with RENATER and french innovative companies (MuQuans, Keopsys, Syrlinks and Kylia), to distribute throughout France an ultra-stable frequency generated at the Observatoire de Paris. REFIMEVE+ will be funded until 2020, under the label “Future Investments” and involves many laboratories: besides the LPL, the SYRTE, RENATER and company Muquans who design, build and oversee the network, 17 other laboratories including the CNES in Toulouse will receive the metrological signal.

REFIMEVE + is a first step to build a network at European level with a first extension considered to Germany with the support of the DFN (German Academic Network). Many other countries are already interested in this possibility. Effective management of equipment at European level could be achieved by including the DANTE consortium and GÉANT2 network that interconnect networks such as RENATER and DFN.

European network of GEANT2, credit geant2 

Many disciplines will benefit from the dissemination of this frequency: the time/frequency metrology, fundamental physics on earth and space, high precision spectroscopy applied to environmental and atmospheric physics. In addition, this instrument will be tested as well as a giant gyro and also as a seismic sensor. The confirmation of the theoretical estimation by experience could pave the way for the development of new deployable seismic sensors thanks to the presence of a wide network of fiber optic around the world.

For further information, we suggest you to read this document   

 Official description of the project (in French)