Geodesy and metrology with a transportable optical clock

TL;DR

This paper demonstrates the first field measurement campaign using a transportable $^{87}$Sr optical lattice clock to determine gravity potential differences, showcasing its potential for geodesy and cross-disciplinary applications.

Contribution

It presents the first successful deployment of a transportable optical clock in the field, enabling practical applications in geodesy and international clock comparison.

Findings

Successful measurement of gravity potential difference over 90 km

Validation of clock consistency between different optical clock types

Demonstration of transportable optical clock capabilities

Abstract

The advent of novel measurement instrumentation can lead to paradigm shifts in scientific research. Optical atomic clocks, due to their unprecedented stability and uncertainty, are already being used to test physical theories and herald a revision of the International System of units (SI). However, to unlock their potential for cross-disciplinary applications such as relativistic geodesy, a major challenge remains. This is their transformation from highly specialized instruments restricted to national metrology laboratories into flexible devices deployable in different locations. Here we report the first field measurement campaign performed with a ubiquitously applicable $^{87}$Sr optical lattice clock. We use it to determine the gravity potential difference between the middle of a mountain and a location 90 km apart, exploiting both local and remote clock comparisons to eliminate potential clock errors. A local comparison with a $^{171}$Yb lattice clock also serves as an important check on the international consistency of independently developed optical clocks. This campaign demonstrates the exciting prospects for transportable optical clocks.