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Participant |
Hume, David | |||||||
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Institution |
NIST - 325 Broadway MS 847.10 - Boulder - CO - USA | |||||||
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Session |
PT4 |
Accepted |
Yes |
Order |
4 |
Time |
15:30 | 20' |
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Talk |
Oral abstract |
Title |
Single-Ion Clocks at NIST as Probes of Time, Relativity and the Fundamental Constants | |||||
| Coauthors | Hume, David B.; Brewer, Samuel B.; Chen, Jwo-Sy; Chou, Chin-Wen; Hankin, Aaron M.; Huang, Yao; Leibrandt, David R.; Wineland, David J.; Rosenband, Till; Bergquist, James C. | |||||||
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Abstract |
The frequency ratio between two optical clock transitions in 27-Al+ and 199-Hg+ has been measured with 17-digit accuracy making it among the most precisely measured constants of nature. Because of the differing sensitivity to variations in the fine-structure constant, α, measurements of this ratio over time place the most stringent present-day constraints on the possible linear drift, α-dot/α = (-1.6 ±2.3)×10^(-17) per year. I will review the general features of these experiments, and describe more recent progress on the Al+ standards, including a demonstration of high sensitivity measurements of relativistic time dilation. The previous generation of Al+ frequency standards reached a total fractional frequency uncertainty of 8.0 × 10 ^(-18) limited primarily by time dilation due to residual harmonic motion of the ions. The latest generation of clocks promises to reduce this further by cooling the Al+ ion close to the quantum mechanical ground state of motion. Further improvements in the accuracy and reliability of these systems may lead to applications in relativistic geodesy as well as more precise measurements of the time variation of fundamental constants. Work supported by AFOSR, ARO, DARPA, and ONR. |
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