Optical-Clock-Based Time Scale
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Optical-Clock-Based Time Scale. / Yao, Jian; Sherman, Jeff A.; Fortier, Tara; Leopardi, Holly; Parker, Thomas E.; McGrew, William; Zhang, Xiaogang; Nicolodi, Daniele; Fasano, Robert; Schäffer, Stefan; Beloy, Kyle; Savory, Joshua; Romisch, Stefania; Oates, Chris; Diddams, Scott; Ludlow, Andrew D.; Levine, Judah.
In: Physical Review Applied, Vol. 12, No. 4, 044069, 30.10.2019.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Optical-Clock-Based Time Scale
AU - Yao, Jian
AU - Sherman, Jeff A.
AU - Fortier, Tara
AU - Leopardi, Holly
AU - Parker, Thomas E.
AU - McGrew, William
AU - Zhang, Xiaogang
AU - Nicolodi, Daniele
AU - Fasano, Robert
AU - Schäffer, Stefan
AU - Beloy, Kyle
AU - Savory, Joshua
AU - Romisch, Stefania
AU - Oates, Chris
AU - Diddams, Scott
AU - Ludlow, Andrew D.
AU - Levine, Judah
N1 - Publisher Copyright: © 2019 US. Published by the American Physical Society.
PY - 2019/10/30
Y1 - 2019/10/30
N2 - 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. Present time scales employ microwave atomic clocks, whose attributes can be combined and averaged in a manner such that the composite is more stable, accurate, and reliable than the output of any individual clock. Over the past decade, clocks operating at optical frequencies have been introduced that are orders of magnitude more stable than any microwave clock. However, in spite of their great potential, these optical clocks cannot be operated continuously, which makes their use in a time scale problematic. We report the development of a hybrid microwave-optical time scale, which only requires the optical clock to run intermittently while relying upon the ensemble of microwave clocks to serve as the flywheel oscillator. The benefit of using a clock ensemble as the flywheel oscillator instead of a single clock can be understood by the Dick-effect limit. This time scale demonstrates for the first time subnanosecond accuracy over a few months, attaining a fractional frequency stability of 1.45 × 10-16 at 30 days and reaching the 10-17 decade at 50 days, with respect to UTC. This time scale significantly improves the accuracy in timekeeping and could change the existing time-scale architectures.
AB - 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. Present time scales employ microwave atomic clocks, whose attributes can be combined and averaged in a manner such that the composite is more stable, accurate, and reliable than the output of any individual clock. Over the past decade, clocks operating at optical frequencies have been introduced that are orders of magnitude more stable than any microwave clock. However, in spite of their great potential, these optical clocks cannot be operated continuously, which makes their use in a time scale problematic. We report the development of a hybrid microwave-optical time scale, which only requires the optical clock to run intermittently while relying upon the ensemble of microwave clocks to serve as the flywheel oscillator. The benefit of using a clock ensemble as the flywheel oscillator instead of a single clock can be understood by the Dick-effect limit. This time scale demonstrates for the first time subnanosecond accuracy over a few months, attaining a fractional frequency stability of 1.45 × 10-16 at 30 days and reaching the 10-17 decade at 50 days, with respect to UTC. This time scale significantly improves the accuracy in timekeeping and could change the existing time-scale architectures.
U2 - 10.1103/PhysRevApplied.12.044069
DO - 10.1103/PhysRevApplied.12.044069
M3 - Journal article
AN - SCOPUS:85074900580
VL - 12
JO - Physical Review Applied
JF - Physical Review Applied
SN - 2331-7019
IS - 4
M1 - 044069
ER -
ID: 324557659