Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Comment on 'Ramsey Spectroscopy, matter-wave interferometry, and the microwave-lensing frequency shift'



Steven R. Jefferts, Thomas P. Heavner, Stephan E. Barlow, Neil Ashby


The authors believe that the theory of the proposed frequency shift by Gibble [1] contains a number of errors that undermine the validity of the proposed effect. Further, because the theory of the proposed frequency shift has multiple errors and because the shift has never been experimentally observed, we believe this shift should not be included as a "correction" to primary frequency standards(PFS) contributing to International Atomic Time (TAI).
Physical Review A


Atomic clock, Primary Frequency Standard, TAI
Created June 18, 2015, Updated November 10, 2018