NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Femtosecond Optical Two-Way Time-Frequency Transfer in the Presence of Motion
Published
Author(s)
Laura C. Sinclair, Hugo Bergeron, William C. Swann, Isaac H. Khader, Kevin C. Cossel, Michael A. Cermak, Nathan R. Newbury, Jean-Daniel Deschenes
Abstract
Platform motion poses significant challenges to high-precision optical time and frequency transfer. We give a detailed description of these challenges and their solutions in comb-based optical two-way time and frequency transfer (O-TWTFT). Specifically, we discuss the breakdown in reciprocity due to relativity and due to asynchronous sampling, the impact of optical and electrical dispersion, and velocity-dependent transceiver calibration. We present a detailed derivation of the equations governing comb-based O-TWTFT in the presence of motion. We describe the implementation of real-time signal processing algorithms based on these equations and demonstrate active synchronization of two sites over turbulent air paths to below a femtosecond time deviation despite effective velocities of 25 m/s, which is the maximum achievable velocity with our physical setup. With the implementation of the time transfer equation derived here, we find no velocity-dependent bias between the synchronized clocks to within the statistical uncertainty of 330 attoseconds.
Citation
Physical Review A
Pub Type
Journals
Keywords
time transfer, optical clocks, optical two-way time-frequency transfer, frequency combs
Sinclair, L.
, Bergeron, H.
, Swann, W.
, Khader, I.
, Cossel, K.
, Cermak, M.
, Newbury, N.
and Deschenes, J.
(2019),
Femtosecond Optical Two-Way Time-Frequency Transfer in the Presence of Motion, Physical Review A
(Accessed October 7, 2025)