Abstract
Singly ionized ytterbium, with ultranarrow optical clock transitions at 467 and 436 nm, is a convenient system for the realization of optical atomic clocks and tests of present-day variation of fundamental constants. We present the first direct measurement of the frequency ratio of these two clock transitions, without reference to a cesium primary standard, and using the same single ion of . The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of . Combining our results with those from other experiments, we report a threefold improvement in the constraint on the time variation of the proton-to-electron mass ratio, , along with an improved constraint on time variation of the fine structure constant, .
- Received 30 June 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.210801
© 2014 American Physical Society
Viewpoint
Time Trials for Fundamental Constants
Published 17 November 2014
Single-ion clocks yield new limits on how much the proton-to-electron mass ratio and the fine structure constant change over time.
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