# Improved Absolute Frequency Measurement of the 171Yb Optical Lattice Clock at KRISS Relative to the SI Second

## TL;DR

This paper reports a highly precise measurement of the $^{171}$Yb optical lattice clock's absolute frequency, significantly reducing uncertainty and aiding the redefinition of the second.

## Contribution

The study provides an improved absolute frequency measurement of the $^{171}$Yb optical lattice clock with a 14-fold reduction in uncertainty compared to previous results.

## Key findings

- Frequency measured as 518,295,836,590,863.38(57) Hz
- Uncertainty reduced by a factor of 14
- Contributes to redefining the second

## Abstract

We measured the absolute frequency of the $^1S_0$ - $^3P_0$ transition of $^{171}$Yb atoms confined in a one-dimensional optical lattice relative to the SI second. The determined frequency was 518 295 836 590 863.38(57) Hz. The uncertainty was reduced by a factor of 14 compared with our previously reported value in 2013 due to the significant improvements in decreasing the systematic uncertainties. This result is expected to contribute to the determination of a new recommended value for the secondary representations of the second.

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Source: https://tomesphere.com/paper/1701.04534