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Search Publications by: William C. Swann (Fed)

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Displaying 1 - 25 of 317

Quantum-limited optical time transfer for future geosynchronous links

June 21, 2023
Author(s)
Emily Caldwell, Jean-Daniel Deschenes, Jennifer Ellis, William C. Swann, Benjamin Stuhl, Hugo Bergeron, Nathan R. Newbury, Laura Sinclair
The combination of optical time transfer and optical clocks opens up the possibility of large-scale free-space networks that connect both ground-based optical clocks and future space-based optical clocks. Such networks promise better tests of general

Impact of Strong Atmospheric Turbulence on Two-Way Optical Time Transfer

May 8, 2023
Author(s)
Laura Sinclair, Emily Caldwell, Jean-Daniel Deschenes, Hugo Bergeron, William C. Swann, Nathan Newbury
Frequency comb based optical time transfer can provide femtosecond-level timing which will support future clock networks. However, for long-distance terrestrial links, non-reciprocal atmospheric turbulence induces a timing penalty. Here, we quantify this

Photon Efficient Optical Time Transfer

April 24, 2022
Author(s)
Emily Caldwell, Laura Sinclair, William C. Swann, Nathan R. Newbury, Benjamin Stuhl, Jean-Daniel Deschenes
We present a novel frequency comb-based system for optical two-way time-frequency transfer to support very long distance free-space links between clocks. Our Photon-Efficient Agile Comb Optical Clock Synchronization (PEACOCS) system supports sub

Frequency Ratio Measurements with 18-Digit Accuracy Using a Network of Optical Clocks

March 24, 2021
Author(s)
Kyle Beloy, Martha I. Bodine, Tobias B. Bothwell, Samuel M. Brewer, Sarah L. Bromley, Jwo-Sy Chen, Jean-Daniel Deschenes, Scott Diddams, Robert J. Fasano, Tara Fortier, Youssef Hassan, David Hume, Dhruv Kedar, Colin J. Kennedy, Isaac Kader, Amanda Koepke, David Leibrandt, Holly Leopardi, Andrew Ludlow, Will McGrew, William Milner, Daniele Nicolodi, Eric Oelker, Tom Parker, John M. Robinson, Stefania Romisch, Stefan A. Schaeffer, Jeffrey Sherman, Laura Sinclair, Lindsay I. Sonderhouse, William C. Swann, Jian Yao, Jun Ye, Xiaogang Zhang
Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other measurement standard and underpinning six out of seven base units in the SI system. By exploiting higher resonance frequencies, optical atomic clocks

Measurement of the 27Al+ and 87Sr absolute optical frequencies

January 21, 2021
Author(s)
Holly Leopardi, Kyle Beloy, Tobias B. Bothwell, Samuel M. Brewer, Sarah L. Bromley, Jwo-Sy Chen, Scott Diddams, Robert J. Fasano, Youssef S. Hassan, David B. Hume, Dhruv Kedar, Colin J. Kennedy, Isaac H. Khader, David R. Leibrandt, Andrew D. Ludlow, William F. McGrew, William R. Milner, Daniele Nicolodi, Eric Oelker, Thomas E. Parker, John M. Robinson, Stefania Romisch, Jeffrey A. Sherman, Lindsay I. Sonderhouse, William C. Swann, Jian Yao, Jun Ye, Xiaogang Zhang, Tara M. Fortier
We perform absolute measurement of the 27Al+ single-ion and 87Sr neutral lattice clock frequencies at the National Institute of Standards and Technology and JILA at the University of Colorado against a global ensemble of primary frequency standards. Over

Femtosecond Time Synchronization of Optical Clocks Off a Flying Quadcopter

April 18, 2019
Author(s)
Hugo Bergeron, Laura C. Sinclair, William C. Swann, Isaac H. Khader, Kevin C. Cossel, Michael A. Cermak, Jean-Daniel Deschenes, Nathan R. Newbury
Optical clock networks promise advances in global navigation, time distribution, coherent sensing, relativity experiments, dark matter searches and other areas1-12. Such networks will need to compare and synchronize clocks over free-space optical links

Measurement of the impact of turbulence anisoplanatism on precision free-space optical time transfer

February 27, 2019
Author(s)
William C. Swann, Martha I. Bodine, Isaac H. Khader, Jean-Daniel Deschenes, Esther Baumann, Laura C. Sinclair, Nathan R. Newbury
Future highly precise free-space optical clock networks will require optically-based two-way time and frequency transfer links. As these networks extend over longer distances, they will include links between moving platforms, e.g. ground-to-air or ground

Femtosecond Optical Two-Way Time-Frequency Transfer in the Presence of Motion

February 22, 2019
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
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

Time Synchronization over a Free-Space Optical Communication Channel

December 20, 2018
Author(s)
Isaac H. Khader, Laura C. Sinclair, William C. Swann, Hugo Bergeron, Nathan R. Newbury, Jean-Daniel Deschenes
Free space optical (FSO) communication channels are typically used to transmit high-speed data between sites over the air. Here we repurpose an FSO digital communication system and use it directly for two-way time transfer. We demonstrate real-time

Femtosecond timekeeping: slip-free optical clockwork for optical timescales

April 3, 2018
Author(s)
Daniel I. Herman, Stefan Droste, Esther Baumann, Jonathan Roslund, Dmitriy Churin, Arman Cingoz, Jean-Daniel Deschenes, Isaac H. Khader, William C. Swann, Craig W. Nelson, Nathan R. Newbury, Ian R. Coddington
The generation of true optical time standards will require the conversion of the highly stable optical frequency output of an optical atomic clock to a high-fidelity time output. We demonstrate comb-based clockwork that phase-coherently integrates ~7x10e20