A strontium lattice clock with 3 × 10−17inaccuracy and its frequency

Concepts

Natural SciencesPhysicsGeodesyInstrumentationMetrologyAtomic ClocksFrequency MetrologyAbsolute FrequencyCesium Fountain ClocksClock AccuracyClock UncertaintyFrequency Ratio MeasurementsOptical ClocksOptical Lattice ClocksSystematic Uncertainty Analysis

TL;DR

The Sr lattice clock’s accuracy approaches that of the best current SI second realizations. The 87Sr lattice clock’s absolute frequency was measured with a 3 × 10⁻¹⁷ inaccuracy, agreeing with other laboratories and improving systematic uncertainty fivefold, thereby enabling precise frequency‑ratio studies for fundamental research, geodesy, and clock evaluation.

Abstract

We have measured the absolute frequency of the optical lattice clock based on 87Sr at PTB with an uncertainty of using two caesium fountain clocks. This is close to the accuracy of today's best realizations of the SI second. The absolute frequency of the 5 s2 1S0 – 5s5p 3P0 transition in 87Sr is .13(17) Hz. Our result is in excellent agreement with recent measurements performed in different laboratories worldwide. We improved the total systematic uncertainty of our Sr frequency standard by a factor of five and reach , opening new prospects for frequency ratio measurements between optical clocks for fundamental research, geodesy or optical clock evaluation.