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

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 …

The last decade has witnessed tremendous progress in research on optical frequency
metrology. Optical frequency standards using optical lattice and single-ion trap technologies …

The pursuit of ever more precise measures of time and frequency motivates redefinition of
the second in terms of an optical atomic transition. To ensure continuity with the current …

Optical clocks are not only powerful tools for prime fundamental research, but are also
deemed for the redefinition of the SI base unit “second,” as they now surpass the …

Optical lattice clocks are at the forefront of frequency metrology. Both the instability and
systematic uncertainty of these clocks have been reported to be two orders of magnitude …

We report on a series of 42 measurements of the transition frequency of the 429 THz (5 s 2)
S 0 1–(5 s 5 p) P 0 3 line in Sr 87 taken over three years from 2017 to 2019. They were …

We present a measurement of the absolute frequency of the 5 s 2 1 S 0 to 5s5p 3 P 0
transition in 87 Sr which is a secondary representation of the SI second. We describe the …

Clock-comparison experiments are among the sharpest existing tests of Lorentz symmetry in
matter. We characterize signals in these experiments arising from modifications to electron …