Optical Clock Networks

QuantumFrontiers researchers play a key role in the development of the next generation of optical clocks for relativistic geodesy. Theirsingle ytterbium ion and strontium lattice clocks represent the frontier for Europe's most accurate devices and are in the first league internationally. In cooperation with several external groups, fibre-optical links were installed between Hannover, Braunschweig, Munich, Paris and London to disseminate optical frequencies over long distances. As a result, optical clocks can now be compared and characterised over long distances without loss of precision.

This whole field, initiated by QuantumFrontiers researchers, will rapidly expand by adding more long-distance connections, e.g. to INRIM in Italy, and further international standard labs. Within QuantumFrontiers, we will develop multi-ensemble clocks and novel approaches for stable frequency references, employ non-classical states and quantum non-demolition readout schemes to perform fast clock comparisons at the 10^-18 level and below. Furthermore, we will bring transportable optical clocks to a new level of integration and reliability for widespread use in geodesy.