National Research Council of Canada. Measurement Science and Standards
2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS), 9-13 July 2017, Besancon, France
absolute frequency measurement; single ion clock; optical atomic clock; GPS frequency link
We report a new measurement of the 445 THz electric quadrupole transition of the strontium ion made using a GPS link to the SI second. Compared to our previous measurement reported in 2012, the operation of the optical clock has been improved in several ways, especially from a reduction of the micromotion shifts, of the black body radiation shift, and of the servo tracking errors. Moreover, the stability of the clock has been improved three-fold with state-preparation. The uncertainty of the optical clock during the measurement campaign was 7 mHz. The uncertainty of the frequency measurement was 0.75 Hz, limited primarily by the GPS link and to a lesser extent by the measurement statistics. The new frequency measurement is in good agreement with previously reported values.
Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS), 2017 Joint Conference of the European.