We review experimental progress on optical atomic clocks and frequency transfer, and
consider the prospects of using these technologies for geodetic measurements. Today …

Atomic frequency standards are used to generate accurate and precise time and frequency,
enabling many communications, synchronization, and navigation systems in modern life …

A clock at a higher altitude ticks faster than one at a lower altitude, in accordance with
Einstein's theory of general relativity. The outstanding stability and accuracy of optical …

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 …

A list of standard reference frequency values (LoF) of quantum transitions from the
microwave to the optical regime has been recommended by the International Committee for …

Within the last decade, optical atomic clocks have surpassed the best cesium clocks, which
are used to realize the unit of time and frequency, in terms of accuracy and stability by about …

This paper outlines the roadmap towards the redefinition of the second, which was recently
updated by the CCTF Task Force created by the CCTF in 2020. The main achievements of …

Transportable strontium optical lattice clocks are developed with a fractional uncertainty of
5.5× 10− 18 for applications outside laboratories. A single clock consists of a spectroscopy …

The extreme precision of optical atomic clocks has led to an anticipated redefinition of the
second by the International System of Units. Furthermore, accuracies pushing the boundary …

Future generations of global navigation satellite systems (GNSSs) can benefit from optical
technologies. Especially optical clocks could back-up or replace the currently used …