From optical to terahertz, frequency metrology with a single ionC. Champenois, G. Hagel, M. Houssin, M. Knoop, M. Vedel, C. Zumsteg and F. VedelAnn. Phys. Fr., 32 2-3 (2007) 25-31DOI: https://doi.org/10.1051/anphys:2008002