2014/07/31 by R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones +7 · 2 citations
Physics and Astronomy · #physics.atom-ph
paper · pdf · doi:10.1103/physrevlett.113.210801
6 pages, 4 figures. Additional citations and minor changes after peer review
arxiv created 2014/10/01 · arxiv updated 2015/06/22
Singly-ionized ytterbium, with ultra-narrow optical clock transitions at 467 nm 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 171Yb+. The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of 6× 10-16. Combining our results with those from other experiments, we report a three-fold improvement in the constraint on the time-variation of the proton-to-electron mass ratio, μ/μ = 0.2(1.1)× 10-16 year-1, along with an improved constraint on time-variation of the fine structure constant, α/α = -0.7(2.1)× 10-17 year-1.