Frequency Ratio Measurements with 18-digit Accuracy Using a Network of Optical Clocks

Abstract

Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other measurement standard and underpinning six out of seven base units in the SI system. By exploiting higher resonance frequencies, optical atomic clocks now achieve greater stability and lower frequency uncertainty than existing primary standards. Here, we report frequency ratios of the ${}^{27}$Al${}^{+}$, ${}^{171}$Yb and ${}^{87}$Sr optical clocks in Boulder, Colorado, measured across an optical network spanned by both fiber and free-space links. These ratios have been evaluated with measurement uncertainties between $6\times 10^{-18}$ and $8\times 10^{-18}$, making them the most accurate reported measurements of frequency ratios to date. This represents a critical step towards redefinition of the SI second and future applications such as relativistic geodesy and tests of fundamental physics.

arXiv comment51 pages, 12 figures, 6 tables

Cited by in corpus (7)

• Coherent phase transfer for real-world twin-field quantum key distribution
• Optical frequency ratio of a ${}^{171}{\mathrm{Yb}}^{+}$ single-ion clock and a ${}^{87}\mathrm{Sr}$ lattice clock
• Absolute frequency of ${}^{87}\mathrm{Sr}$ at $1.8\times 10^{-16}$ uncertainty by reference to remote Primary Frequency Standards
• Optical Atomic Clock Comparison through Turbulent Air
• Frequency ratio of an ${}^{115}$In${}^{+}$ ion clock and a ${}^{87}$Sr optical lattice clock
• Extended gravitational clock compass: new exact solutions and simulations
• Extraordinary low systematic frequency shifts in bi-colour thulium optical clock