Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks

Weyers, S.; Gerginov, Vladislav; Kazda, Michael; Rahm, Johannes; Lipphardt, B.; Dobrev, Georgi; Gibble, Kurt

doi:10.1088/1681-7575/aae008

Cited by 124 publications

(86 citation statements)

References 86 publications

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“…The frequency transfer uncertainty in this value can be calculated from Eq. [70][71][72][73][74], and a single Rb fountain (SYRTE FORb) [32], with between five and eight of these being present in any given month. The SYRTE and PTB Cs fountains were present most often and have the most weight.…”

Section: Appendix B: Frequency Connection To Psfsmentioning

confidence: 99%

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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Section: Appendix B: Frequency Connection To Psfsmentioning

confidence: 99%

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

McGrew

Zhang

Leopardi

et al. 2019

Optica

119

110

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“…For the calculation of this factor, the single particle reduced matrix element of µ (1) q is given by…”

Section: Theorymentioning

confidence: 99%

“…Howbeit, use of microwave atomic clocks are extremely robust in numerous scientific and industrial fields including satellite navigation systems, network synchronization, timekeeping applications and defense systems etc. [1] owing to their several order lower frequencies than the optical clock frequencies. Mostly microwave clocks are based on the neutral atoms, but making these clocks using singly charged ions have many advantages.…”

Section: Introductionmentioning

confidence: 99%

Roles of electron correlation effects for the accurate determination of gj factors of low-lying states of Cd+113 and their applications to atomic clocks

Han

Sahoo

et al. 2019

Phys. Rev. A

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We investigate roles of electron correlation effects in the determination of gj factors of the ns 2 S 1/2 (n=5,6,7), np 2 P 1/2,3/2 (n=5,6), 5d 2 D 3/2,5/2 , and 4f 2 F 5/2,7/2 states of the singly ionized cadmium (Cd + ) ion. Single and double excited configurations along with important valence triple excited configurations through relativistic coupled-cluster (RCC) theory are taken into account for incorporating electron correlation effects in our calculations. We find significant contributions from the triples to the lower S and P states for attaining high accuracy results. The contributions of Breit interaction and lower-order quantum electrodynamics effects, such as vacuum polarization and self-energy corrections, are also estimated using the RCC theory and are quoted explicitly. In addition, we present energies of the aforementioned states from our calculations and compare them with the experimental results to validate gj values. Using the gj factor of the ground state, systematical shift due to the Zeeman effect in the microwave clock frequency of the |5s 2 S 1/2 , F = 0, mF = 0 ↔ |5s 2 S 1/2 , F = 1, mF = 0 transition in 113 Cd + ion has been estimated.

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“…Optical clocks [1][2][3][4][5][6][7][8], whose frequencies are about five orders of magnitude larger than the microwave atomic clocks, have potential better stability and accuracy than that of the cesium (Cs) fountain microwave clocks used to define the second [9][10][11][12]. Thus they attract a lot of interest in precision measurements [13].…”

Section: Introductionmentioning

confidence: 99%

Realization of phase locking in good-bad-cavity active optical clock

Shi¹,

Pan²,

Chen³

2019

Opt. Express

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The residual cavity-pulling effect limits further narrowing of linewidth in dualwavelength (DW) good-bad-cavity active optical clocks (AOCs). In this paper, we for the first time experimentally realize the cavity-length stabilization of the 1064/1470 nm DW-AOCs by utilizing the phase locking technique of two independent 1064 nm good-cavity lasers. The frequency tracking accuracy between the two main-cavities of DW-AOCs is better than 3 × 10 −16 at 1 s, and can reach 1 × 10 −17 at 1000 s. Each 1470 nm bad-cavity laser achieves a most probable linewidth of 53 Hz, which is about a quarter of that without phase locking. The influence of the asynchronous cavity-lengths variation between two DW laser systems is suppressed.

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Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks

Cited by 124 publications

References 86 publications

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

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

Roles of electron correlation effects for the accurate determination of gj factors of low-lying states of Cd+113 and their applications to atomic clocks

Realization of phase locking in good-bad-cavity active optical clock

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