First Evaluation and Frequency Measurement of the Strontium Optical Lattice Clock at NIM

Lin, Yang‐I; Wang, Qiang; Li, Ye; Meng, Fanqi; Lin, Bo; Zang, Erjun; Sun, Zhen; Fang, Fang; Li, Tianchu; Fang, Zhongyuan

doi:10.1088/0256-307x/32/9/090601

Cited by 65 publications

(56 citation statements)

References 30 publications

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“…*ssr+ah*sah+rb*srb+sensm 120))+dmu*(x-58305)/365.225)+sensq 0))+dq*(x-58305)/365.225)+sensalph* 120))+dalph*(xA summary of this work, as well as six other Yb absolute frequency measurements (yellow)[18,[27][28][29][30][31], and seventeen Sr measurements (red)[9,10,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48].Sr measurements are multiplied by the Yb/Sr ratio and the error bars are expanded as descibed in the main text. The fit function (orange) constrains possible variation of the Yb/Cs ratio, and the shaded region represents the 1σ uncertainty of the fit.…”

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“…measurements[18,[27][28][29][30][31], ν avg Yb = 518 295 836 590 863.714(98) Hz. For the Sr frequency, we likewise determine a weighted average of 17 previous measurements[9,10,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], ν avg Sr = 429 228 004 229 873.055(58) Hz. The frequency ratio derived from absolute frequency measurements is therefore, R avg abs = ν avg Yb /ν avg Sr = 1.207 507 039 343 337 86…”

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Towards the optical second: verifying optical clocks at the SI limit

McGrew

Zhang

Leopardi

et al. 2019

Optica

119

110

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The pursuit of ever more precise measures of time and frequency is likely to lead to the eventual redefinition of the second in terms of an optical atomic transition. To ensure continuity with the current definition, based on a microwave transition between hyperfine levels in ground-state 133 Cs, it is necessary to measure the absolute frequency of candidate standards, which is done by comparing against a primary cesium reference. A key verification of this process can be achieved by performing a loop closure-comparing frequency ratios derived from absolute frequency measurements against ratios determined from direct optical comparisons. We measure the 1 S 0 → 3 P 0 transition of 171 Yb by comparing the clock frequency to an international frequency standard with the aid of a maser ensemble serving as a flywheel oscillator. Our measurements consist of 79 separate runs spanning eight months, and we determine the absolute frequency to be 518 295 836 590 863.71(11) Hz, the uncertainty of which is equivalent to a fractional frequency of 2.1 × 10 −16 .This absolute frequency measurement, the most accurate reported for any transition, allows us to close the Cs-Yb-Sr-Cs frequency measurement loop at an uncertainty of <3×10 −16 , limited by the current realization of the SI second. We use these measurements to tighten the constraints on variation of the electron-to-proton mass ratio, µ = m e /m p . Incorporating our measurements with the entire record of Yb and Sr absolute frequency measurements, we infer a coupling coefficient to gravitational potential of k µ = (−1.9 ± 9.4) × 10 −7 and a drift with respect to time oḟ µ µ = (5.3 ± 6.5) × 10 −17 /yr. arXiv:1811.05885v1 [physics.atom-ph]

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Towards the optical second: verifying optical clocks at the SI limit

McGrew

Zhang

Leopardi

et al. 2019

Optica

119

110

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“…The instability of the TOC is dominated by the performance of the interrogation laser [45] through the Dick effect [50]. It is lower than achieved in typical single ion clocks [3,12,31,51], and comparable to many high performance lattice clocks [2,32,[52][53][54][55][56].…”

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confidence: 99%

Transportable Clocks Move with the Times

Godun

2017

Physics

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We present a transportable optical clock (TOC) with 87 Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4 × 10 −17 , which is currently limited by the statistics of the determination of the residual lattice light shift, and an instability of 1.3 × 10 −15 = ffiffi ffi τ p with an averaging time τ in seconds. Measurements confirm that the systematic uncertainty can be reduced to below the design goal of 1 × 10 −17 . To our knowledge, these are the best uncertainties and instabilities reported for any transportable clock to date. For autonomous operation, the TOC has been installed in an airconditioned car trailer. It is suitable for chronometric leveling with submeter resolution as well as for intercontinental cross-linking of optical clocks, which is essential for a redefinition of the International System of Units (SI) second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and its development is an important step to space-borne optical clocks. DOI: 10.1103/PhysRevLett.118.073601 The best clocks reach fractional systematic uncertainties of a few 10 −18 [1-3] and instabilities near or even below 10 ,4-6], surpassing the clocks realizing the International System of Units (SI) second in both aspects by 2 orders of magnitude. These achievements have triggered a discussion about a redefinition of the SI second [7,8] and push the frontiers of precision spectroscopy [2,9,10] as well as tests of fundamental physics [10][11][12][13]. Further, these clocks enable chronometric leveling [14][15][16][17][18] with relevant resolution, where gravitational redshifts are exploited to measure height differences.So far, the operation of optical clocks has been constrained to laboratories. However, applications like chronometric leveling require transportable clocks to provide the necessary flexibility in the choice of measurement sites. Transportable optical clocks (TOCs) are highly interesting for frequency metrology and time keeping as well, enabling a consistent worldwide network of ultraprecise clocks. Although comparisons at the full performance level of state-of-the-art optical clocks are possible through a few specialized optical fiber links [19][20][21][22] on a continental scale [17,23], intercontinental links are restricted to satellite-based methods that do not reach the clock performance [24]. In contrast, a transfer standard enables world-wide interconnections between optical clocks exploiting their exquisitely small uncertainty and low instability. It will thus benefit the efforts towards a redefinition of the SI second.Making optical clocks compact and robust for transport is the first phase in granting a wide community of users access to these devices [25][26][27]. Furthermore, transportability is a relevant step towards applications of optical clocks in space. Although developments in these directions are ongoing [28][29][30][31], to our knowledge, the o...

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“…As well as the five direct optical frequency ratio measurements already discussed, these included 16 new absolute frequency measurements: one each of the 1S-2S transition in 1 H [18], the optical clock transitions in 171 Yb [19] and 88 Sr + [20] and the ground state hyperfine transition in 87 Rb [21], two each of the E2 [9,14] and E3 [9,15] transitions in 171 Yb + and the reference transition in 40 Ca + [22], and six of the optical clock transition in 87 Sr [23,24,25,26,27,28]. In addition, a correction [29] was submitted to a previously-used absolute frquency measurement of the optical clock transition in 199 Hg [30] and one earlier absolute frequency measurement of the reference transition in 40 Ca + [31] was withdrawn as new data from the same group suggested that the systematic frequency shifts may have been underestimated in this measurement [22].…”

Section: Analysis Of Data Available In September 2015mentioning

confidence: 99%