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
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 2
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) The CIPM List of Recommended Frequency Standard Values: Guidelines and Procedures, by F. Riehle, P. Gill, F. Arias, L. Robertsson, soon be on Metrologia. 3
Some photos 4
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. frequencies for the realizations of the meter frequencies for secondary representation of the second 5
Evolution in L and TF Length Time and Frequency Evolution of the fractional uncertainty to realize the metre according to the mise en 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 directly related to the caesium atomic clock, green dots refer to published estimated standard uncertaines to realize the unperturbed line centre. 6
Commonly used wavelengths for the realization of the metre in dimensional metrology by interferometry Frequency / THz Fractional uncertainty Wavelength / nm Laser / absorber 473.612 7 1.5 x 10 6 632.990 8 HeNe unstabilized 473.612 353 604 2.1 x 10 11 632.991 212 58 HeNe / I 2 551.580 162 400 4.5 x 10 11 543.515 663 608 HeNe / I 2 563.260 223 513 8.9 x 10 12 532.245 036 104 2f (Nd:YAG) / I 2 7
Secondary Representation of the Second (2017) Frequency / Hz Fractional uncertainty Transition Status 6 834 682 610.904 312 6 6 x 10 16 87 Rb Revised 2017 310 7 x 10 16 Ground state hfs 2015 value 429 228 004 229 873.0 4 x 10 16 87 Sr neutral atom, Revised 2017 873.2 5 x 10 16 5s 21 S 0 5s5p 3 P 0 2015 value 444 779 044 095 486.5 1.5 x 10 15 88 Sr + ion, Revised 2017 486.6 1.6 x 10 15 5s 2 S 1/2 4d 2 D 5/2 2015 value 518 295 836 590 863.6 5 x 10 16 171 Yb neutral atom, Revised 2017 864.0 2 x 10 15 6s 21 S 0 6s6p 3 P 0 2015 value 642 121 496 772 645.0 6 x 10 16 171 Yb + ion, 6s 2 S 1/2 5d 2 F 7/2 Not revised 688 358 979 309 308.3 6 x 10 16 171 Yb + ion, Not revised 6s 2 S 1/2 5d 2 D 3/2 1 064 721 609 899 145.3 1.9 x 10 15 199 Hg + ion, Not revised 5d 10 6s 2 S 1/2 5d 9 6s 22 D 5/2 1 121 015 393 207 857.3 1.9 x 10 15 27 Al + ion, Not revised 3s 21 S 0 3s3p 3 P 0 1 128 575 290 808 154.4 5 x 10 16 199 Hg neutral atom, 6s 21 S 0 6s6p 3 P 0 New 2017 8
Present status as of 2017 Optical frequency ratio measurement 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 methods 1: 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. 9
115In + transition 5s 2 1 S 0 5s5p 3 P 0 q1 nu1 1267402452899920.0 690.0 [vonzanthier2000] q2 nu1 1267402452901265.0 256.0 [Wang2007a] q3 nu1 1267402452900967.0 63.0 [Wang2007b] (removed because of inconsistency) q4 nu1 1267402452901049.9 20.7 [Ohtsubo2017 accept.] CIPM 2003: 1267402452899920 Hz + 3.6 x 10 13 Recalculation: 1267402452901050.2866 Hz + 20.62 Hz WGFS CCL-CCTF 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( 115 In) is 1267402452901050 Hz u c /y = 1.6 x 10-14
171Yb transition 6s 2 1 S 0 6s5p 3 P 0 ; latt. clock WGFS CCL-CCTF q24 nu8 518295836590864.0 28.0 [Kohno2009] q25 nu8 518295836590863.1 2.0 [Yasuda2012] q26 nu8 518295836590865.2 0.7 [Lemke2009] q27 nu8 518295836590863.5 8.1 [Park2013] q28 nu8 518295836590863.59 0.31 [Pizzocaro2017] q29 nu8 518295836590863.38 0.57 [Kim2017] 171 Yb / 87 Sr q70 nu8_over_ 1.2075070393433412 1.7e-15 [Akamatsu2014aErrata] q71 nu8_over_ 1.20750703934333776 2.9e-16 [Takamoto2015] q72 nu8_over_ 1.207507039343337749 5.5e-17 [Nemitz2016] CIPM LoF: Recalculation: f( 171 Yb) = 518 295 836 590 864.0 + - 2 10-15 f( 171 Yb) = 518 295 836 590 863.6440 Hz +- 0.0609 Hz The adopted value of f( 171 Yb) 518 295 836 590 863.6 Hz u c /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 87 Sr 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]
87Sr transition 5s 2 1 S 0 5s5p 3 P 0 latt. clock q40 q41 q42 q43 q44 q45 q46 q47 q48 q49 q50 q51 q52 q53 q54 q55 87 Sr/ 40 Ca + 429228004229874.0 429228004229873.65 429228004229873.6 429228004229874.1 429228004229872.9 429228004229873.9 429228004229872.0 429228004229873.56 429228004229873.7 429228004229873.13 429228004229873.10 429228004229872.92 429228004229872.97 429228004229873.04 429228004229872.97 429228004229872.99 1.1 0.37 1.1 2.4 0.5 1.4 1.6 0.49 1.4 0.17 0.13 0.12 0.16 0.11 0.40 0.18 [Boyd2007] [Campbell2008] [Baillard2008] [Hong2009] [Falke2011] [Yamaguchi2012] [Akamatsu2014b] [Tanabe2015] [Lin2015] [Falke2014] [LeTargat2013] [Lodewyck2016] [Grebing2016(Oct14)] [Grebing2016(Jun15)] [Hachisu2017] [Hachisu2017b] q75 _over_nu13 1.0442433345296416 2.5e-15 [Matsubara2012] 87 Sr/ 87 Rb q76 _over_nu14 62801.453800512435 2.1e-11 [Lodewyck2016] WGFS CCL-CCTF
87Sr transition 5s 2 1 S 0 5s5p 3 P 0 (update) CIPM LoF: 429228004229873.2 Hz + 5 x 10 16 WGFS CCL-CCTF Recalculation: 429228004229873.0356 Hz + 0.047 Hz The adopted value of f( 171 Yb) 429 228 004 229 873.0 Hz u c /y = 4 x 10-16 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]
40Ca + transition 4s 2 S 1/2 3d 2 D 5/2 (update) q56 nu13 411042129776393.2 3.0 [Chwalla2009] q57 nu13 411042129776398.4 1.2 [Matsubara2012] q58 nu13 411042129776400.5 1.2 [Huang2015,2012value] q59 nu13 411042129776401.7 1.1 [Huang2015,2014/15value] WGFS CCL-CCTF CIPM LoF: Recalculation: f( 40 Ca + ) = 411 042 129 776 398.4 Hz + - 1.2 x 10-14 f( 40 Ca + ) = 411 042 129 776 399.7963 Hz ± 0.5458 Hz. The adopted value of f( 40 Ca + ) = 411 042 129 776 399.8 Hz u c /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 40 Ca + 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. A new definition should therefore take place as early as possible and as late as necessary. 15
Prediction of the timeline for redefinition of the second 3 clocks / ~10 3 comparisons / 5 10 3 clocks / 3 10 Regular contribution to TAI Uncertainties ~ two order of magnitude better than Cs Independent measurements of the same optical clock in different institute Continuity with present definition: independent measurements w.r.t. three independent Cs primary clocks Measurement reports covering at least ten days 2 comp. b/w 5 clocks / / / 5 10 Frequency ratios Validation and decision for optical standard CCTF CGPM CCTF CGPM CGPM 2017 2018 2020 2022 2025 2026 2030 16 CCTF Strategy Document, Annex 1 (Towards a new definition of the second in the SI, F. Riehle)
Present status as of 2017 Absolute frequency measurement Continuity with present definition: independent measurements w.r.t. three independent Cs primary clocks Convergence of the absolute frequency value of the Sr clock transition after 10 years of measurements! 17
CCL-CCTF WGFS procedure for updating the CIPM List of Frequencies CCL-CCTF WGFS For information of frequency standards CIPM For information of practical realisations of the metre CCTF Proposals for approval of frequency standards Copy for information CCL-CCTF WGFS CCL Proposals for approval of practical realisations of the metre Submission of frequencies for SRS and other T/F applications Submission of frequencies for 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 ) 19
Report from TCTF/TCL JWG on Optical Frequency Metrology Masami Yasuda Time Standards Group National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST) TCTF Meeting Delhi, India XX Nov. 2017