Transportable optical clocks for key comparisons - 22IEM01 TOCK

In recent years, significant progress with optical clocks has been achieved, such that they clearly outperform current primary standards of time and frequency. The currently established key comparison for time and frequency uses satellite-based techniques to provide international consistency with 10E-16 fractional uncertainty. Optical fibre links between a few NMI laboratories in Europe are available and can enable clock comparisons with low 1E-18 uncertainty, but these are limited by relativistic effects. To overcome these limitations and to compare optical clocks that cannot be interconnected via optical fibre links, this project will develop travelling frequency standards with performance exceeding the current state-of-the-art. The use of these transportable optical clock (TOCs) as frequency standards will be evaluated by the project and their feasibility for use in future key comparisons will be demonstrated.