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Search Publications by: Tara Fortier (Fed)

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Displaying 1 - 25 of 178

High-Stability Single-Ion Clock with 5.5 x 10^-19 Systematic Uncertainty

April 21, 2025
Author(s)
Mason Marshall, Daniel Rodriguez Castillo, Willa Dworschack, Alexander Aeppli, Kyungtae Kim, Dahyeon Lee, William Warfield, Nicholas Nardelli, Tara Fortier, Jun Ye, David Ray Leibrandt, David Hume
We report a single-ion optical atomic clock with fractional frequency uncertainty of 5.5 x 10^-19 and frequency stability of 3.5 x 10^-16/sqrttau/s}, based on quantum logic spectroscopy of a single 27Al+ ion. A co-trapped 25Mg+ ion provides sympathetic

Optical and microwave metrology at the 10-18 level with an Er/Yb:glass frequency comb

February 5, 2023
Author(s)
Nicholas Nardelli, Holly Leopardi, THOMAS SCHIBLI, Tara Fortier
Optical frequency combs are an essential tool for precision metrology experiments ranging in application from remote spectroscopic sensing of trace gases to the characterization and comparison of optical atomic clocks for precision time-keeping and

Improved interspecies optical clock comparisons through differential spectroscopy

November 28, 2022
Author(s)
May E. Kim, Will McGrew, Nicholas Nardelli, Ethan Clements, Youssef Hassan, Xiaogang Zhang, Jose Valencia, Holly Leopardi, David Hume, Tara Fortier, Andrew Ludlow, David Leibrandt
Comparisons of high-accuracy optical atomic clocks \citeLudlow2015} are essential for precision tests of fundamental physics \citeSafronova2018}, relativistic geodesy \citeMcGrew2018, Grotti2018, Delva2019}, and the anticipated redefinition of the SI

10 GHz Generation with Ultra-Low Phase Noise via the Transfer Oscillator Technique

February 8, 2022
Author(s)
Nicholas Nardelli, Tara Fortier, Marco Pomponio, Esther Baumann, Craig Nelson, Thomas Schibli, Archita Hati
We generate 10 GHz microwave signals using the transfer oscillator technique, which employs digital and RF analog techniques to coherently remove the additive noise from an optical frequency comb. This method permits transfer of the frequency stability and

High-performance, compact optical standard

September 15, 2021
Author(s)
Zachary Newman, Vincent N. Maurice, Tara Fortier, Connor Fredrick, Scott Diddams, John Kitching, Matthew Hummon
We describe a high-performance, compact optical frequency standard based on a microfabricated Rb vapor cell and a low-noise, external cavity diode laser operating on the Rb two-photon transition at 778 nm. The optical standard achieves an instability of 1

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

Coherent Optical Clock Down-Conversion for Microwave Frequencies with 10-18 Instability

May 22, 2020
Author(s)
Takuma Nakamura, Josue Davila-Rodriguez, Holly Leopardi, Jeffrey Sherman, Tara Fortier, Xiaojun Xie, Joe C. Campbell, Will McGrew, Xiaogang Zhang, Youssef Hassan, Daniele Nicolodi, Kyle Beloy, Andrew Ludlow, Scott Diddams, Franklyn Quinlan
Optical atomic clocks are poised to redefine the SI second, thanks to stability and accuracy more than one hundred times better than the current microwave atomic clock standard. However, the best optical clocks have not seen their performance transferred

On-Wafer Metrology of a Transmission Line Integrated Terahertz Source

May 10, 2020
Author(s)
Kassiopeia A. Smith, Bryan T. Bosworth, Nicholas R. Jungwirth, Jerome G. Cheron, Nathan D. Orloff, Christian J. Long, Dylan F. Williams, Richard A. Chamberlin, Franklyn J. Quinlan, Tara M. Fortier, Ari D. Feldman
A combination of on-wafer metrology and high-frequency network analysis was implemented to measure the response of transmission-line integrated Er-GaAs and InGaAs photomixers up to 1 THz to support the telecommunication and electronics industry.

Frequency-comb spectroscopy on pure quantum states of a single molecular ion

March 27, 2020
Author(s)
Chin-wen Chou, Alejandra L. Collopy, Christoph Kurz, Yiheng Lin, Michael E. Harding, Philipp N. Plessow, Tara M. Fortier, Scott A. Diddams, Dietrich G. Leibfried, David R. Leibrandt
Spectroscopy is a powerful tool for studying molecular properties and is commonly performed on large thermal ensembles of molecules that are perturbed by motional shifts and interactions with the environment and one another, resulting in convoluted spectra

Optical-Clock-Based Time Scale

October 30, 2019
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 backbone for critical navigation tools such as the global positioning system (GPS). Present

Ramsey-Borde Matter-Wave Interferometry for Laser Frequency Stabilization at 10 -16 Frequency Instability and Below

August 13, 2019
Author(s)
Judith B. Olson, Todd Sheerin, Holly Leopardi, Roger C. Brown, Richard W. Fox, Rick Stoner, Tara M. Fortier, Christopher W. Oates, Andrew D. Ludlow
We demonstrate Ramsey-Borde (RB) atom interferometry for high performance laser stabilization with fractional frequency instability −16 for timescales between 10 and 1000s. The RB spectroscopy laser interrogates two counterpropagating 40Ca beams on the 1S

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

July 15, 2019
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+ 2S1/2 ground electronic state, Ahfs = -596 254 250.981(45) Hz, with improved uncertainties. Both