VLBI experiments with the dissemination of a common clock via coherent optical fiber link

Abstract

Atomic clock synchronization plays an important role in both radio astronomical and geodetic Very Long Baseline Interferometry, as time and frequency standards are provided by station clocks. National metrological institutes have recently started streaming (via optical fiber links) frequency references from ultra-stable clocks based on optical line transitions in Strontium/Ytterbium laser-cooled lattices. Optical lattice clocks are already two orders of magnitude more stable than the radio station H-masers. In this talk we will describe how the Italian Quantum Backbone (IQB) was used to carry out a series of European geodetic VLBI experiments in which the Medicina and Matera radio stations were connected to the same remote clock located at the Italian Metrological institute in Turin, via the IQB optical link. In the foreseeable future a European VLBI network of radio stations could be connected via optical fiber links to a single very high-performance clock hosted by a European Metrological institute.