Overview of Frequency Metrology at NMIJ

Transcription

1 Overview of Frequency Metrology at NMIJ Tomonari SUZUYAMA National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST) APMP2018 TCTF meeting RESORTS WORLD SENTOSA, Singapore November 26-27, 2018

2 Structure of NMIJ The National Institute of Advanced Industrial Science and Technology (AIST) NMIJ Energy and Environment Life Science and Biotechnology Information Technology and Human Factors Materials and Chemistry Electronics and Manufacturing Geological Survey of Japan National Metrology Institute of Japan

3 Structure of NMIJ Structure of NMIJ Integration for Innovation Research Institute for Engineering Measurement Research Institute for Physical Measurement Time Standards Group Frequency Measurement Group Quantum Electrical Standards Group Applied Electrical Standards Group Electromagnetic Measurement Group Radio-Frequency Standards Group Electromagnetic Fields Standards Group Thermometry Research Group Frontier Thermometry Research Group Applied Radiometry Research Group Photometry and Radiometry Research Group Quantum Optical Measurement Group Research Institute for Material and Chemical Measurement Research Institute for Measurement and Analytical Instrumentation Center for Quality Management of Metrology Research Promotion Division of NMIJ

4 Time Standards Group Members: M. Yasuda A. Iwasa K. Hagimoto T. Suzuyama D. Akamatsu T. Tanabe T. Kobayashi K. Hosaka(Research Planning Office) Main tasks Upgrading UTC(NMIJ) Time and frequency transfer Integration for Innovation Calibration service: time and frequency Yb and Sr optical lattice clocks Narrow linewidth lasers

5 UTC(NMIJ) generation system and time transfer link UTC(NMIJ) is generated by reference signal from one hydrogen maser steered by an AOG. Clocks at NMIJ - 4 hydrogen masers 1 RH401A made by Anritsu 1 VCH-1003M made by VREMYA 1 SD1T01A made by Anritsu 1 CH1-75A made by KVARZ + new one made by? CH1-75A is the reference oscillator of UTC(NMIJ) - 2 Cs clocks 5071A with high performance beam tube Time Transfer Link - UTC PPP (GPS carrier phase) using Z12-T: main time transfer tool - TWSTFT : backup tool (No satellite, not operate now)

6 UTC-UTC(NMIJ) : Timescale 2 years (October 2016 October 2018)

7 UTC-UTC(NMIJ) : Frequency deviation 2 years (October 2016 October 2018)

8 Remote Frequency Calibration Service by NMIJ (1) GPS UTC(NMIJ) AIST(NMIJ) GPS Receiver jcss Calibration Certificate Registered establishment site Data server Web Published Data Data Download Internal oscillator is synchronized to UTC(NMIJ) with the NMIJ web site data Data Upload Internet

9 Remote Frequency Calibration Service by NMIJ (2) Item Mode Number (total 23) GPS Receiver Cs Free run 4 2 JRC JQE102 1 GCET 1 Freqtime FT001A Rb NMIJ-DO 13 8 GCET 5 Freqtime FT001S Rb GPS-DO 2 1 JRC JQE102 1 GCET Rb Free run 1 1 JRC JQE102 BVA NMIJ-DO 1 1 Freqtime FT001S OCXO NMIJ-DO 1 1 Freqtime FT001S VCXO GPS-DO 1 JRC JQE102-VCXO The number of clients are growing year by year. User for Time & Frequency and Rotational speed

10 Optical lattice clocks at NMIJ Yb/Sr ratio (18) D. Akamatsu, Opt. Express 22, 7898 (2014) Yb optical lattice clock 1 Absolute Frequency Measurement (2.0) Hz M. Yasuda, APEX 5, (2012) Sr/Yb optical lattice clock 2 Absolute Frequency Measurement (49) Hz T. Tanabe, JPSJ 84, (2015) Dual Mode Operation D. Akamatsu, IEEE UFFC 65, 1069 (2018) Yb optical lattice clock 3 Uncertainty evaluation / Long-term operation T. Kobayashi, IEEE UFFC, in press (2018)

11 Laser-controlled cold Yb atom source for transportable optical lattice clock MOT laser (399 nm) (horizontal pairs not shown) MOT coil Emission laser (405 nm) ~70 mw Yb Blue MOT Emitted atoms To vacuum pump Actual image Ytterbium oxide (Yb 2 O 3, Not in scale) Distance b/w MOT & Yb 2 O 3 : ~ 10 cm J. Phys. Soc. Jpn. 86, (2017).

12 Application of the deep learning for improving the synchronous accuracy of UTC and UTC(NMIJ) Basic idea & question : Is it possible to improve the synchronous accuracy of UTC and UTC(k) by using the deep learning technique? Time difference data between UTC and HM HM(Hydrogen maser) (master oscillator of UTC(NMIJ)) GOAL : improvement of the synchronous accuracy of UTC and UTC(NMIJ) 3. Feedback to the frequency adjustment of HM by the frequency adjuster(aog). 1. Time difference data are supplied into the Deep Neural Network(DNN). 2. The trained-dnn predict the future time difference.

13 Application of the deep learning for improving the synchronous accuracy of UTC and UTC(NMIJ) Current status : We implemented and trained a one-dimensional convolutional neural network (1D-CNN*) as the DNN, and then obtained the first result of prediction. (* F. Chollet, Deep learning with Python (Manning Publications, 2017)) * Manuscript in preparation for submission to the Japanese Journal of Applied Physics - The result of prediction (red circle) in this figure was obtained by repeating the short-term prediction over the whole data as follows, the 5 points of actual data were fed into the trained 1D-CNN and the trained 1D-CNN predicted the one point ahead. - In this sense, the performance of the 1D-CNN as the predictor is at an very-early stage. Next to do : - The prediction without supplying the actual data to the 1D-CNN Blue line : actual time difference data of UTC and HM after subtraction the quadratic component as a function of MJD Red circle : the result of prediction by the 1D-CNN - The prediction in consideration of environmental data of the room, where the HM is located (temperature, atmospheric pressure and humidity, etc.)

14 Radio-Frequency Standards Group Members: H. Iida T. Ikegami* S. Yanagimachi* A. Takamizawa* M. Kinoshita Y. Tojima K. Shimaoka Anton Widarta I. Hirano** K. Watabe** Main tasks(t&f Field) Cs atomic fountains* Integration for Innovation Cryocooled cryogenic sapphire oscillator*,** Calibration service: phase noise*,** ** Electromagnetic Measurement Group

15 15 Cesium Fountain: NMIJ-F2 Ramsey cavity Selection cavity Detection beam Ion pump 55 l/s 10 cm C-field coil Magnetic shielding Detection chamber NEG pump Integration for Innovation Microwave cavities which are part of the vacuum vessel (S. R. Jefferts et al., Proc. of the 1998 IEEE FCS, p. 6) Decrease of the uncertainty caused by microwave power dependence High power laser 50 mw per cooling-beam Optical pumping to m F =0 (K. Szymaniec et al., Appl. Phys. B, to be published.) Increase in detected atoms ( atoms) Improvement of frequency stability Cs Cooling beam Trapping chamber Helmholtz coils Cryocooled Sapphire oscillator (cryocso) (J. G. Hartnett et al., Appl. Phys. Lett. 100, (2012).) Local oscillator with <10-15 at 1s Improvement of frequency stability

16 16 Frequency stability Integration for Innovation Extrapolation of zero density t -1/2 High density t -1/2 Frequency at zero atomic density is extrapolated from alternation measurement between high density and low density. Density ratio = 4:1. 10 cycles for high density, 40 cycles for low density. s ext (t) 4s h (t). s ext (t): at extrapolation, s h (t): at high density. Good enough to get s ext (20 days) ~ 10-16

17 Preliminary error budget Effect Correction ( ) Uncertainty ( ) Second-order Zeeman Blackbody radiation Cold collision (+2) 0.2 Distributed cavity phase Microwave power dependence Gravity Microwave lensing Microwave switch 0 Not yet Total type B (except MW switch)

18 Frequency Measurement Group Members H. Inaba (Group Leader) Y. Shimizu K. Kashiwagi S. Okubo M. Wada K. Nakamura (Postdoctoral Researcher) Main tasks Scientific research regarding development and applications of frequency combs Calibration service of laser frequency Technology transfer to company Recent main research activities 1. Astro-comb in the visible wavelength region 2. Frequency comb with wide frequency interval (>10 GHz) 3. Frequency comb with extremely high frequency stability 4. Precise thermometry using Dual-comb spectroscopy

19 Thank you for your attention!