Absolute frequency measurement with uncertainty below $1\times 10^{-15}$ using International Atomic Time

Abstract

The absolute frequency of the ${}^{87}\mathrm{Sr}$ clock transition measured in 2015 was reevaluated using an improved frequency link to the SI second. The scale interval of International Atomic Time (TAI) that we used as the reference was calibrated for an evaluation interval of five days instead of the conventional interval of one month which is regularly employed in Circular T. The calibration on a five-day basis removed the uncertainty in assimilating the TAI scale of the five-day mean to that of the one-month mean. The reevaluation resulted in the total uncertainty of $10^{-16}$ level for the first time without local cesium fountains. Since there are presumably no correlations among systematic shifts of cesium fountains worldwide, the measurement is not limited by the systematic uncertainty of a specific primary frequency standard.

arXiv commentApplied Physics B, in press

References in corpus (11)

• Frequency Comparison of Two High-Accuracy Al+ Optical Clocks
• Systematic evaluation of an atomic clock at 2e-18 total uncertainty
• Single-Ion Atomic Clock with $3\times 10^{-18}$ Systematic Uncertainty
• Experimenting an optical second with strontium lattice clocks
• A strontium lattice clock with $3\times 10^{-17}$ inaccuracy and its frequency
• Realization of a time-scale with an accurate optical lattice clock
• Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock
• Stability Transfer between Two Clock Lasers Operating at Different Wavelengths for Absolute Frequency Measurement of Clock Transition in 87Sr
• Spectroscopy and frequency measurement of the ${}^{87}$Sr clock transition by laser linewidth transfer using an optical frequency comb
• Intermittent optical frequency measurements to reduce the dead time uncertainty of frequency link
• Improved frequency measurement of the ${}^1{S}_0$-${}^3{P}_0$ clock transition in ${}^{87}$Sr using the Cs fountain clock at NMIJ as a transfer oscillator

Cited by in corpus (14)

• Geodesy and metrology with a transportable optical clock
• Long term measurement of the ${}^{87}$Sr clock frequency at the limit of primary Cs clocks
• SI-traceable measurement of an optical frequency at low $10^{-16}$ level without a local primary standard
• A strontium optical lattice clock with $1\times 10^{-17}$ uncertainty and measurement of its absolute frequency
• Demonstration of the nearly continuous operation of an ${}^{171}$Yb optical lattice clock for half a year
• Absolute frequency measurement of the ${}^2$S${}_{1/2}{\to }^2$F${}_{7/2}$ optical clock transition in ${}^{171}$Yb${}^{+}$ with an uncertainty of $4\times 10^{-16}$ using a frequency link to International Atomic Time
• Precision measurements on the ${}^{138}$Ba${}^{+}$ $6s^2{S}_{1/2}-5d^2{D}_{5/2}$ clock transition
• Absolute frequency of ${}^{87}\mathrm{Sr}$ at $1.8\times 10^{-16}$ uncertainty by reference to remote Primary Frequency Standards
• Frequency measurement of the clock transition of an indium ion sympathetically-cooled in a linear trap
• Intercombination line frequencies in ${}^{171}$Yb validated with the clock transition
• Towards Adoption of an Optical Second: Verifying Optical Clocks at the SI Limit
• Months-long real-time generation of a time scale based on an optical clock
• Improved absolute frequency measurement of ${}^{171}$Yb at NMIJ with uncertainty below $2\times 10^{-16}$
• Absolute frequency measurement of a Lu${}^{+}$ ${(}^3{\mathrm{D}}_1)$ optical frequency standard via link to international atomic time