Report from TCTF/TCL JWG on Optical Frequency Metrology Masami Yasuda 1 and Tetsuya Ido 2 1 Time Standards Group, National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST) 2 Space-Time Standards Laboratory, National Institute of Information and Communcations Technology (NICT) TCTF Meeting Delhi, India 27 Nov. 2017
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Report from TCTF/TCL JWG on Optical Frequency Metrology
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Report from TCTF/TCL JWGon Optical Frequency Metrology
Masami Yasuda1 and Tetsuya Ido2
1Time Standards Group, National Metrology Institute of Japan (NMIJ),National Institute of Advanced Industrial Science and Technology (AIST)2Space-Time Standards Laboratory,National Institute of Information and Communcations Technology (NICT)
TCTF MeetingDelhi, India27 Nov. 2017
APMP TCTF/TCL JWG on OFM from 2007• Main subjects of the WG:
• Optical frequency comb research activities• Optical clock research activities• Microwave and optical frequency dissemination• Optical frequency combs and CCL‐K11
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Report on CCTF (CCL‐CCTF WGFS & WGPSFS)• Period: 6 June 2017• Place: BIPM (Sevres) • Participants: (CCL‐CCTF WGFS)
• Dr. John Bernard, NRC (Ottawa)• Dr. Davide Calonico, INRIM (Turin)• Dr. Zhanjun Fang, NIM (Beijing)• Prof. Feng‐Lei Hong, NMIJ/AIST (Tsukuba)• Mr. Sang‐Wook Hwang, KRISS (Daejeon)• Dr. Nikolai Koshelyaevsky, VNIIFTRI (Moscow)• Dr. Helen Margolis, NPL (Teddington)• Mr. Andrey Naumov, VNIIFTRI (Moscow)• Dr. Chris Oates, NIST (Gaithersburg)• Dr. Ekkehard Peik, PTB (Braunschweig)• Dr. Anders Wallin, MIKES (Espoo)• Dr. Masami Yasuda, NMIJ/AIST (Tsukuba)• Dr. Dai‐Hyuk Yu, KRISS (Daejeon)
• Participants: (CCTF WGPSFS)• Mr. Laurent‐Guy, METAS (Bern‐Wabern)• Dr. Tetsuya Ido, NICT (Tokyo)• Dr. Tomonari Suzuyama, NMIJ/AIST (Tsukuba)
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“The CIPM List of Recommended Frequency Standard Values:Guidelines and Procedures”,by F. Riehle, P. Gill, F. Arias, L. Robertsson,soon be on Metrologia.
Some photos
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CCL‐CCTF WGFS• The objectives of the CCL‐CCTF WGFS are:
• To make recommendations to the CCL for radiations to be used for the realization of the definition of the metre and to make recommendations to the CCTF for radiations to be used as secondary representations of the second;
• To maintain, together with the BIPM, the list of recommended frequency standard values and wavelength values for applications including the practical realization of the definition of the metre and secondary representations of the second;
• To take responsibility for key comparisons of standard frequencies such as CCL‐K11;
• To respond to future needs of both the CCL and CCTF concerning standard frequencies relevant to the respective communities.
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frequencies for the realizations of the meterfrequencies for secondary representation of the second
Evolution in L and TF
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Length Time and Frequency
Evolution of the fractional uncertainty to realize the metre according to the miseen pratique together with two practical limitations i.e. the fractional uncertainty when measuring the length of a gauge block (dashed line) and the fractional uncertainty introduced by the diffraction correction in an interferometric length measurement (dashed – dotted line).
Evolution of the fractional uncertainty to realize the unperturbed line centre of primary atomic caesium clocks (squares) and of optical frequency standards (dots).Red dots show the fractional uncertainties of optical frequency standards directlyrelated to the caesium atomic clock, green dots refer to published estimated standard uncertaines to realize the unperturbed line centre.
Commonly used wavelengths for the realization of the metre in dimensional metrology by interferometry
Together with the direct absolute frequency measurement w.r.t.the Cs clocks, these frequency ratio measurements form an overdetermined set of data.
Two independent approaches to confirm the methods1: Least squares method to determine the “best” estimates of the frequency values by Margolis and Gill.2: Examination of closed loops in a graph theory framework by Robertsson.
The four values available are inconsistent as Wang2007a and Wang7b have very different uncertainties but result from the same data set and there is not a clear explanation for this difference. It was decided to keep the measurement with the larger uncertainty [Wang2007a]. From the least square procedure it turned out that the uncertainty of [vonZanthier2000] is not compatible with the other data. Thus the uncertainty given in the original publication [vonZanthier2000] was increased to 690 Hz to make it statistically more consistent. [Ohtsubo2017] has an uncertainty that is more than ten times smaller than the other ones and this uncertainty was enlarged by a factor of 3 to 20.7 Hz in the calculation.
The adopted value of f(115In) is 1267402452901050 Hz uc/y = 1.6 x 10-14
The adopted value of f(171Yb) 518 295 836 590 863.6 Hz uc/y = 5 x 10-16
has been calculated by the methods presented in * with the data from the source table attached below. The estimated standard uncertainty of 5 x 10-16 takes into account the uncertainty of the 87Sr value of 4 x 10-16 governing the evaluation procedure and also takes into account the smaller database.* [Margolis, Gill 2015, Robertsson 2015, Oates 2017, Riehle et al 2017]
has been calculated by the methods presented in * with the data from the source table attached below. The recommended uncertainty is the same as that of the most accurate comparison between the Cs PFS at LNE-SYRTE and PTB via an optical fibre link [Guena2017] i.e. 4 x 10-16.
• * [Margolis, Gill 2015, Robertsson 2015, Oates 2017, Riehle et al 2017]
The adopted value of f(40Ca+) = 411 042 129 776 399.8 Hz uc/y = 2.4 x 10-15
has been calculated by the methods presented in * with the data from the source table attached below. Since [Chwalla2009] is not compatible with the other data, the uncertainty given in the original publication was increased to 3 Hz to make it statistically more consistent. This value has very little effect, and so the recommended frequency value comes essentially only from measurements made by two labs. Thus the final 40Ca+ uncertainty was enlarged by a factor of 2.* [Margolis, Gill 2015, Robertsson 2015, Oates 2017, Riehle et al 2017]
Prediction of the timeline for redefinition of the second• On the frequency standards
• At least three different optical clocks having demonstrated validated uncertainties of about two orders of magnitude better than the Cs (few 10‐18),
• At least three independent measurements of the same optical clock in different institutes are compared,
• At least five ratios between optical frequency standards, each measured at least twice by independent laboratories and agreeing.
• On the continuity with the present definition• At least three independent measurements of optical frequency standards w.r.t. three independent Cs primary clocks (Cs fountain uncertainties are the limitation).
• On the intervals of operation of optical clocks• Regular measurement reports over at least ten days submitted for TAI.
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A new definition should therefore take placeas early as possible and as late as necessary.
Prediction of the timeline for redefinition of the second
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3 clocks∆ / ~10 Uncertainties ~ two order of magnitude better than Cs
3 comparisons∆ / 5 10
Independent measurements of the same optical clock in different institute
3 clocks∆ / 3 10
Continuity with present definition: independent measurementsw.r.t. three independent Cs primary clocks
Regular contribution to TAI Measurement reports covering at least ten days
2 comp. b/w 5 clocks∆ / / / 5 10 Frequency ratios
Validation and decision for optical standard
CCTF Strategy Document, Annex 1 (Towards a new definition of the second in the SI, F. Riehle)
2017 2020 2022 2025 2026 20302018
CGPMCCTF CCTF CGPM CGPM
Present status as of 2017• Absolute frequency measurement
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Convergence of the absolute frequency value of the Sr clock transition after 10 years of measurements!
Continuity with present definition: independent measurementsw.r.t. three independent Cs primary clocks
CCL-CCTFWGFS
CCL-CCTF WGFS procedurefor updating the CIPM List of Frequencies
CIPM
CCTF CCL
CCL-CCTFWGFS
Copy for information
Proposals for approval of frequency standards
For information of frequency standards
For informationof practical realisations
of the metre
Submission of frequenciesfor SRS and other T/F
applications
Submission of frequenciesfor practical realisations
of the metre
Proposals for approval of practical realisations
of the metre
Towards the next CCTF• Next CCTF will be held in 2020.• Details not yet clear.• More frequency ratio data needed.• Long term operation of optical clocks needed for TAI.• More Cs fountain contribution needed.
• (# of working Cs fountain clocks decreasing…)
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Report from TCTF/TCL JWGon Optical Frequency Metrology
Masami YasudaTime Standards Group
National Metrology Institute of Japan (NMIJ),National Institute of Advanced Industrial Science and Technology (AIST)