Contributing to TAI with a secondary representation of the SI second

Guéna, Jocelyne; Abgrall, M.; Clairon, A.; Bize, S.

doi:10.1088/0026-1394/51/1/108

Cited by 79 publications

(97 citation statements)

References 73 publications

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“…This can be done with a statistical uncertainty of 1 part in 10 −16 , and therefore at the accuracy limit of primary frequency standards defining the scale interval of TAI [57]. This illustrates how TAI provides worldwide access to the accuracy of Cs fountains.…”

Section: Advanced Timekeepingmentioning

confidence: 96%

“…Following this submission, the BIPM and the Working Group defined how frequency standards based on Secondary Representations will be handled by the BIPM and how they will be included into the Circular T. The Working Group was renamed Working Group on Primary and Secondary Frequency Standards and it was decided that calibrations produced by LNE-SYRTE with FO2-Rb could be included into Circular T and, since July 2013, contribute to steering TAI. This was the first time that a transition other than the Cs hyperfine transition was used to steer TAI [57].…”

Section: Advanced Timekeepingmentioning

confidence: 99%

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Atomic fountains and optical clocks at SYRTE: Status and perspectives

Abgrall

Chupin

Sarlo

et al. 2015

Comptes Rendus. Physique

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In this article, we report on the work done with the LNE-SYRTE atomic clock ensemble during the last 10 years. We cover progress made in atomic fountains and in their application to timekeeping. We also cover the development of optical lattice clocks based on strontium and on mercury. We report on tests of fundamental physical laws made with these highly accurate atomic clocks. We also report on work relevant to a future possible redefinition of the SI second. IntroductionResearch on highly accurate atomic frequency standards and their applications is making fast and steady progress. The quest for ever increased accuracy is advancing hand in hand with advances in quantum physics, with better understanding and manipulation of atomic systems, with exploration of fundamental laws of nature and with the development of important services and infrastructures for science and society. The quest for increased accuracy is also a powerful incentive to innovation in such areas as lasers, laser stabilization, low noise electronics, stable oscillators, low noise detection of optical signals, fiber devices and cold-atom based instrumentation for ground or space applications. Finally, in addition to enhancing existing applications, improved accuracy leads to new applications.This article focuses on key achievements and trends of the last 10 years. Over this period of time, the first generation of laser-cooled standards, using the atomic fountain geometry, reached maturity and had large impact on international timekeeping. The typical accuracy of these frequency standards, 2 parts in 10 16 , is now permanently accessible both locally and globally. At the same time, a new generation of optical clocks showed tremendous and steady improvement, gaining more than two orders of magnitude in a decade. To date, an accuracy of 6.4 × 10 −18 [1] was reported. Similarly, major improvements occurred in many other aspects of optical frequency metrology, notably in optical frequency combs and optical fiber links.In this article, we will report on developments of the LNE-SYRTE atomic clock ensemble since our 2004 report in the Special Issue of the Comptes Rendus de l'Académie des sciences on Fundamental Metrology [2]. This work exemplifies many of the above mentioned features of research on highly accurate atomic frequency standards. We will focus on frequency standards and their impact on timescales and timekeeping, on clock comparisons, including optical-to-microwave comparisons with combs, and their applications. Several

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Section: Advanced Timekeepingmentioning

confidence: 96%

Section: Advanced Timekeepingmentioning

confidence: 99%

Atomic fountains and optical clocks at SYRTE: Status and perspectives

Abgrall

Chupin

Sarlo

et al. 2015

Comptes Rendus. Physique

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“…Atomic clocks have been generally used for timing applications [1][2][3][4] , precise tests of fundamental symmetries [5,6] , searching dark matters [7,8] , and quantum information science [9,10] . Cesium fountains have been contributing to International Atomic Time (TAI) as the most accurate primary frequency standards for more than a decade [11,12] , and rubidium fountains have been accepted as a secondary standard [1,3] .…”

mentioning

confidence: 99%

“…Cesium fountains have been contributing to International Atomic Time (TAI) as the most accurate primary frequency standards for more than a decade [11,12] , and rubidium fountains have been accepted as a secondary standard [1,3] . To date, atomic fountain clocks (AFCs) have achieved a low 1 × 10 −16 level of total uncertainties and long-term stability of a low 1 × 10 −16 even to the 1 × 10 −17 level [1][2][3][4] . Optical lattice clocks and ion clocks progress rapidly, and now have achieved lower systematic uncertainty and stability of the 1 × 10 −18 level [13][14][15][16][17][18][19] .…”

mentioning

confidence: 99%

Untitled

2017

中国光学快报

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The environmental perturbation on atoms is a key factor restricting the performance of atomic frequency standards, especially in the long-term scale. In this Letter, we perform a real-time noise distinguish (RTND) to an atomic clock to decrease the uncertainty of the atomic clock beyond the level that is attained by the current controlling method. In RTND, the related parameters of the clock are monitored in real time by using the calibrated sensors, and their effects on the clock frequency are calculated. By subtracting the effects from the error signal, the local oscillator is treated as equivalently locked to the unperturbed atomic levels. In order to perform quantitative tests, we engineer time-varying noise much larger than the intrinsic noise in our fountain atomic clock. By using RTND, the influences of the added noises are detected and subtracted precisely from the error signals before feeding back to the reference oscillator. The result shows that the statistical uncertainty of our fountain clock is improved by an order of magnitude to 2 × 10 −15 . Besides, the frequency offset introduced by the noise is also corrected, while the systematic uncertainty is unaffected.

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“…As the most active field of time and frequency standards, atomic fountain clocks and optical clocks have shown great importance in the definition of the Système International (SI) second [1] , timing applications [2] , and numerous precise measurements [3,4] . Over several decades of development, 133 Cs and 87 Rb atomic fountain clocks have achieved a 1.1 × 10 −16 uncertainty [5] with a few parts in a 1 × 10 17 instability [2] .…”

mentioning

confidence: 99%

Closely interleaved self-comparison method applied to precise measurement

et al. 2016

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A self-comparison method with closely interleaved switching states is analyzed and used to evaluate some type-B uncertainties of an 87 Rb atomic fountain clock. Free from additional frequency reference, the method can be applied to a running fountain to reach a precision beyond its uncertainty. A verification experiment proves an uncertainty of 9.2 × 10 −16 at an averaging time of 242500 s. Further, the method is applied to measure light shift, and no visible relative frequency shift is found in the fountain within the uncertainty of 2.1 × 10 −15 . When applied to the evaluation of a cold collisional shift, the result gives a −2.2 × 10 −15 shift with a 9.5 × 10 −16 uncertainty.

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Contributing to TAI with a secondary representation of the SI second

Cited by 79 publications

References 73 publications

Atomic fountains and optical clocks at SYRTE: Status and perspectives

Atomic fountains and optical clocks at SYRTE: Status and perspectives

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Closely interleaved self-comparison method applied to precise measurement

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