Time and Frequency Activities at KRISS Dai-Hyuk Yu Center for Time and Frequency Metrology, Division of Physical Metrology Korea Research Institute of Standards and Science (KRISS) dhyu@kriss.re.kr
Time and Frequency Transfer (GNSS) Receivers of GNSS time transfer Asia link VSAT GNSS Antennas Asia-EU link VSAT Ashtech Z12-T: 2 sets (master Rx until Oct. 2017) Multi-ch. P-code/PPP Septentrio PolaRx3e: 1 set Multi-ch. P-code/PPP GPS & GLONASS Piktime TTS4: 1 set Multi-ch. P-code/PPP GPS & GLONASS & Galileo Dicom GTR51: 1 set (master Rx from Nov. 2017) Multi-ch. P-code/PPP GPS & GLONASS & Galileo - Receiver Calibration by NICT new experimental room
Time and Frequency Transfer (TWSTFT) Two Way Satellite Time and Frequency Transfer Asia link via Eutelsat-172A KRISS NICT TL SATRE modem & SDR supplied by TL Asia-Europe link vis AM22 PTB - KRISS, NIM, NTST, VNIIFTRI Study on Improvement of carrier phase measurement
KRISS-F1 Cs & Rb double fountain as the second fountain at KRISS. (111)-configuration Ion getter pump Window Small getter pumps Flight tube C-filed bobbin Magnetic shields Interrogation cavity (Cs) Interrogation cavity (Rb) Detection chamber Selection cavity (Cs) Selection cavity (Rb) MOT coils Trap chamber Shimming coils Magnetic shields Cs fountain Contributes to TAI Improves UTC(KRIS) Gives the best Cs SI second and its uncertainty to Yb optical lattice clock Rb fountian Secondary representation of the SI second Precision measurement of clock transition frequency with respect to Cs fountain
Optical Pumping Fiber collimator Fluorescent collector
Estimated Stability with Optical Pumping Rabi spectrum TOF signal (a.u.) 1.0 0.8 0.6 0.4 0.2 0.0-3 -2-1 0 1 2 3 5 4 3 2 1 Initial m state OM w/o OP OM with OP OM w/o OP OM with OP MOT w/o OP MOT with OP Short-term stability σ y (1 s) 10-12 10-13 10-14 LO: CSO LO: H-maser QPN OM (1x10-13 ) MOT (2x10-14 ) MOT / OP (1x10-14 ) Measured Expected H-maser OM / OP (4.5x10-14 ) Current limit Laser noise 10-3 10-2 10-1 10 0 0 0 20 40 60 80 Time (ms) Atom number (a.u)
Current uncertainty budget of KRISS-F1 (Cs) Effect Uncertainty ( 10-16 ) Second order Zeeman 0.5 Cold collision (Cs-Cs) 2* Blackbody radiation 0.6 Gravity 0.5 Background gas collision <0.5 Cavity pulling <0.1 Rabi / Ramsey pulling <0.1 Microwave lensing 0.4 Microwave spectrum <0.1 Microwave leakage 0.5 AC stark shift (laser light) <0.1 DCP (m0) <0.2* DCP (m1) 0.2 DCP (m2) <0.1 Total 2.4* dp (ppm) 60 40 20 0-20 -40-60 0 1 2 3 4 5 6 7 8 9 10 11 dp (ppm) 0.20 0.15 0.10 0.05 Calcualation 0.00 0.0 0.5 1.0 1.5 2.0 2.5 b b 0.11 ppm (8 10-18 )
Yb Optical Lattice Clock
Yb absolute frequency measurement Frequency - f(cipm2015) (Hz) 30 20 10 2 1 0-1 -2-10 -3-20 -30 included in CCTF2017 1.9x10-15 1.1x10-15 CIPM2015 CCTF2017 9.6x10-16 f(cipm2015) = 518 295 836 590 864(1) Hz f(cctf2017) = 518 295 836 590 863.6(3) Hz NMIJ(2009) NIST(2009) NMIJ(2012) KRISS(2013) NMIJ(2014) RIKEN(2015) RIKEN(2016) INRIM(2016) Campaign 2016 Dec. Campaign 2017 Feb. KRISS Total Data Kim et. Al., JJAP (2017) 171 Yb absolute frequency measured (referenced to TT): 518 295 836 590 863.38(57) Current systematic uncertainty: 8.3x10-17
Optical Clock Comparison (TWSTFT) KRISS Yb NICT Sr (R-1.207507039343300)x10-15 44 42 40 38 36 Yb/Sr Frequency Ratio by recommended values by local comparison by remote comparison R(Yb/Sr) = 1.207 507 039 343 337 86(70) u = 5.8x10-16 CIPM2013 NMIJ2014 RIKEN2014 CIPM2015 RIKEN2015 INRIM/PTB2017 CCTF2017 KRISS/NICT2017 --
2 nd Yb Clock
2 nd Yb Clock BBR chamber: BBR uncertainty 3 10-18 E-filed electrode
2 nd Clock Laser 2 nd Clock laser cavity Mirror crystaline coating: thermal limit 4.3x10-17 Medium long cavity (30 cm) Expected stability at room temp.(10-18 @10000 s) Finesse
Atomic gravimeter Atomic gravimeter Absolute gravimeter with high sensitivity using atomic coherence Physical constant measurement Gravitational constant G, fine-structure constant a Test of general relativity Testing of equivalence principle, measurement of gravitational redshift and gravitational wave Other Applications Inertial sensor for navigation Precision measurement of geoid watt balance project Investigation of under ground structure and resource T height 0 time I II Laser pulse T I II
Atomic gravimeter: Stability g/g=1.6x10-8 @1 s 2x10-7 measured g tidal theory 10-5 10-6 1.1x10-6 @1s Allan deviation 2015.11.13 2016.11.07 2017.09.06 g/g 1x10-7 0-1x10-7 g/g 10-7 10-8 10-9 10-10 1.5x10-7 @1s 1.6x10-8 @1s 10 0 10 1 10 2 10 3 10 4 10 5 τ (s) Target accuracy Target stability g/g 57912 57913 57914 57915 57916 10-7 10-8 10-9 10-10 MJD T=75ms, period=1.2s, before tidal correction T=75ms, period=1.2s, after tidal correction g/g=3.8x10-8 @ 1s 10 0 10 1 10 2 10 3 10 4 10 5 τ (s)
Miniature Atomic Clock Potential applications in civil and military industries Information and communications, navigation, GPS, smart grid, satellite, timing devices, sensor watching, etc. Target performance Stability 2.5ⅹ10-10 @ 1s Volume 25 cm 3, Power consumption 125 mw Physics package CPT resonance curves Clock transition
Dissemination of the Korea Standard Time Broadcasting of Time Signal (call sign: HLA) 5 MHz, 5 kw Time service through internet NTP time server at KRISS 260 million/day
LF Station in Korea Project: 2015~2019 Signal: KST + Information (public, commercial?) Carrier frequency: 65 khz 500 km Reference and Control station Transmitting station Synchronization with UTC(KRIS)
Test Station Spec. Place: ~Center of Korea Peninsula Antenna height: 132 m Carrier Frequency 65 khz Transmitter Power: 50 ~ 100 kw Expected operation: early 2019
Generator/Receiver
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