Absolute frequency measurement of the ${}^{40}$Ca${}^{+}$ clock transition using a GNSS link to the SI second

M. Guevara-Bertsch, M. K. Joshi, M. I Hussain +2

We report the absolute frequency measurement of the $4s$ ${}^2{S}_{1/2}\leftrightarrow 3d$ ${}^2{D}_{5/2}$ ${}^{40}$Ca${}^{+}$ clock transition with respect to the SI second. To perform t…