Absolute frequency of theSr+885sS1∕2

Abstract

A Cs referenced optical frequency comb system has been used to measure the center frequency of the 5s 2 S 1/2 -4d 2 D 5/2 transition at 445 THz in a single, trapped, and laser-cooled 88 Sr + ion. The transition frequency SD = 444 779 044 095 510 Hz± 50 Hz ͑1͒ is obtained, when corrected for systematic shifts. A detailed calculation of the estimated systematic shifts is presented which yields improved values for the various shift parameters including blackbody and electric quadrupole moment shifts. PACS number(s): 32.30.Jc, 32.80.Pj, 06.20.Fn, 06.30.Ft FIG. 1. Partial energy level diagram of 88 Sr + showing the principal transitions used in cooling, fluorescence detection, repumping, and probing of the reference 445-THz ͑674 nm͒ transition. 70 012507-1 FIG. 2. Schematic diagram of the NRC femtosecond laser frequency comb system.

Precision measurement of the branching fractions of the5pP1/22state inSrLikforman1, Tugayé2, Guibal3 et al. 2016Phys. Rev. A19180View full textAdd to dashboardCite

“…Theoretical works on 88 Sr + are largely motivated by the use the dipole-forbidden "clock" 5s 2 S 1/2 → 4d 2 D 5/2 Sr + transition (ν = 446 THz, λ = 674 nm) as a secondary frequency standard [16,17,26]. Indeed, in 2006 the International Committee for Weights and Measures (CIPM) has included this transition among the recommended secondary representation of the second [27].…”

Optical Atomic Clocks Could Redefine Unit of Time

“…In addition, these references underpin the SI system which forms the basis of physical measurement. New experimental systems employing dipole forbidden optical transitions in trapped and laser-cooled ions and neutral atoms have been shown to be excellent nextgeneration realizations of ultra-accurate frequency references [3][4][5][6][7][8][9][10][11][12][13][14]. Such systems now have evaluated accuracies that exceed the current realizations of the definition of the SI second as realized by a microwave transition in Cs atoms [15].…”

Black-body radiation shifts and theoretical contributions to atomic clock research

“…Significant recent progress in optical spectroscopy and measurement techniques has led to the achievement of relative standard uncertainties in optical frequency standards that are comparable to the Cs microwave benchmark. In 2006, the International Committee for Weights and Measures (CIPM) recommended that the following transitions frequencies be used as secondary representations of the second [5]: ground-state hyperfine microwave transition in 87 Rb [6], [7], 5s 2 S 1/2 − 4d 2 D 5/2 optical transition of the 88 Sr + ion [8], [9], 5d 10 6s 2 S 1/2 (F = 0) − 5d 9 6s 2 2 D 5/2 (F = 2) optical transition in 199 Hg + ion [10], [11], 6s 2 S 1/2 (F = 0) − 5d 2 D 5/2 (F = 2) optical transition in 171 Yb + ion [12], [13] and 5s 2 1 S 0 − 5s5p 3 P 0 transition in 87 Sr neutral atom [14], 1 Email: msafrono@udel.edu [15], [16]. With better stability and accuracy, as well as extremely low systematic perturbations, such optical frequency standards can reach a systematic fractional uncertainty of order 10 −18 [9], [17].…”