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William McGrew (Fed)

Publications

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

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 C. 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

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

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

Optical-Clock-Based Time Scale

Author(s)
Jian Yao, Jeffrey A. Sherman, Tara M. Fortier, Andrew D. Ludlow, Holly Leopardi, Thomas E. Parker, William F. McGrew, Scott A. Diddams, Judah Levine
A time scale is a procedure for accurately and continuously marking the passage of time. It is exemplified by coordinated universal time (UTC), and provides the

Measurements of 25Mg+ and 27Al+ magnetic constants for improved ion clock accuracy

Author(s)
Samuel M. Brewer, Jwo-Sy Chen, Aaron M. Hankin, Ethan Clements, Chin-wen Chou, Kyle Beloy, Will McGrew, Xiaogang Zhang, Robert J. Fasano, Daniele Nicolodi, Holly Leopardi, Tara Fortier, Scott Diddams, Andrew Ludlow, David J. Wineland, David Leibrandt, David Hume
We have measured the quadratic Zeeman coefficient for the 3P0 excited electronic state in 27Al+, C2=-71.944(24) MHz/T2 and the hyperfine constant of the 25Mg+

Towards the optical second: verifying optical clocks at the SI limit

Author(s)
William F. McGrew, Xiaogang Zhang, Robert J. Fasano, Holly Leopardi, Daniele Nicolodi, Kyle P. Beloy, Jian Yao, Jeffrey A. Sherman, Stefan A. Schaeffer, Joshua J. Savory, Stefania Romisch, Christopher W. Oates, Thomas E. Parker, Tara M. Fortier, Andrew D. Ludlow
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
Created October 9, 2019, Updated June 30, 2022