Improved Frequency Ratio Measurement with 87Sr and 171Yb Optical Lattice Clocks at NMIJ

TL;DR

This paper reports highly precise frequency ratio measurements between $^{87}$Sr and $^{171}$Yb optical lattice clocks at NMIJ, achieving a threefold improvement in measurement uncertainty and contributing to international timekeeping standards.

Contribution

The study introduces enhanced $^{87}$Sr optical lattice clock modifications and provides the most precise frequency ratio measurement to date between these two atomic clocks.

Findings

Frequency ratio $ u_{Yb}/ u_{Sr}$ measured as 1.20750703934333858(49)$_{sys}$(6)$_{stat}$.

Measurement uncertainty reduced to $4.1 imes 10^{-16}$, 3.4 times smaller than previous results.

Enhanced clock stability and accuracy at NMIJ for international time standards.

Abstract

We report improved frequency ratio measurement with $^{87}$Sr and $^{171}$Yb optical lattice clocks at the National Metrology Institute of Japan (NMIJ). The $^{87}$Sr optical lattice clock is enhanced with several major modifications and is re-evaluated with a reduced uncertainty of $1.1\times10^{-16}$. We employed a $^{171}$Yb optical lattice clock with an uncertainty of $4\times10^{-16}$ that was developed for contributing to International Atomic Time (TAI). The measurement result is $\nu_{\mathrm{Yb}}/\nu_{\mathrm{Sr}}$ = 1.207 507 039 343 338 58(49)$_{\mathrm{sys}}$(6)$_{\mathrm{stat}}$ with a fractional uncertainty of $4.1\times10^{-16}$, which is 3.4 times smaller than our previous measurement result.