Frequency dissemination with a 86-km optical fibre for fundamental tests of physics

A 43-km optical link has been developed between LPL and LNE-SYRTE, to transfer a primary reference frequency in the RF or microwave range. The phase noise introduced by the fluctuations of the propagation delay is compensated using a delay line. The resolution has been improved by increasing the transferred frequency up to 9 GHz. This link was used to compare a molecular optical clock in LPL to a primary reference in SYRTE, which leads to a test of the stability of electron to proton mass ratio.