Development of atomic clocks and frequency transfer techniques at three laboratories around area

Yuko Hanado(1), Feng‐Lei Hong(2), Hidetoshi Katori(3)

(1) National Institute of Information and Communications Technology (NICT) (2) National Metrology Institute of Japan (NMIJ) (3) and Riken Agenda

• Background • Report from o University of Tokyo and RIKEN o NMIJ o NICT • Summary of activities in 4 institutes • Summary Background

Tokyo area = One of active areas on R&D of atomic clocks

10 km Agenda

• Background • Report from o University of Tokyo and RIKEN o NMIJ o NICT • Summary of activities in 4 institutes • Summary Optical Lattice Clocks, Cavities, and Fiber Link under development at UT and Riken No Dead time operation: highly stable clock utilizing stable L.O. (20K silicon cavity) Cryo‐Sr@70K Hg @RT 87Sr 87 Sr Hg Hg Cryogenic Sr 87Sr clock @70K

2011.04‐ Cryogenic Sr clock @70K Hg clock @RT

Sync. operation to 87Sr 87Sr Hg Hg evaluate 10‐17‐10‐18

Demonstration of N=1000 advantage 87 88 Sr Sr QPN limit stability 10‐17@1600s 2010‐2011 Agenda

• Background • Report from o University of Tokyo and RIKEN o NMIJ o NICT • Summary of activities in 4 institutes • Summary Optical lattice clocks at NMIJ

Yb optical lattice clock Sr-Yb dual optical lattice clock

1 3 171 S0(F = 1/2)‐ P0(F = 1/2) transition in Yb 1) Contribution to the Sr lattice clock f = 518 295 836 590 863.1(2.0) Hz community; (Fractional uncertainty 3.9×10‐15) 2) As a second optical clock to be used for the evaluation of the Yb lattice clock; M. Yasuda et al., Appl. Phys. Express vol. 5, 3) Measurement of the Sr/Yb frequency ratio 102401, Sep. 2012. with an uncertainty beyond the Cs limit; 4) Contribution to the experimental Secondary representations of the demonstration of alpha variation. second (Oct., 2012) Atomic fountains at NMIJ

2.0E-14 f（NMIJ‐F1)‐f(TAI) f(PFS)‐f(TAI)

) 1.0E-14

y(NMIJ-F1)-y(TAI 0.0E+00

2011.3.11 Earthquake

-1.0E-14 53800 54300 54800 55300 55800 MJD Calibration of TAI using NMIJ-F1

• 25 reports to BIPM in recent 4 years until Feb.2011. • The operation has stopped since March 2011 (Earthquake). • We will need some time for recovery. NMIJ-F2 (under construction) UTC(NMIJ) generation system and time transfer link at NMIJ

Europe air- link conditioned Storehouse ASIA link

Temperature controlled chambers CH1-75A Earth station for 5071A configuration • UTC(NMIJ) is generated by reference signal form one H-maser steered by an AOG. • Clocks at NMIJ - 4 H-masers 1 RH401A made by Anritsu 1 SD1T01A made by Anritu 1 CH1-75A made by KVARZ 1 VCH-1003M made by VREMYA - 3-5 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 Agenda

• Background • Report from o University of Tokyo and RIKEN o NMIJ o NICT • Summary of activities in 4 institutes • Summary Atomic clocks at NICT 1D optical lattice clock 40Ca+ single-ion optical clock with spin-polarized 87Sr atoms Systematic uncertainty: 5e-16 Systematic uncertainty: 2e-15 Contribution to secondary Contribution to CIPM Recommend representation of the second Direct frequency comparison Comparison with WIPM in China with Univ.Tokyo using fiber link 5 mm by GPS link Operating Freq. ref. at NICT Ref. for In+-Ca+ clock development

Absolute frequency in five groups Absolute frequency measured at NICT 77 403 Direct comparison 402 76 401

75 400 399

74 398

397 73 396

Absolute frequency frequency Absolute 395

72 - 411 042 129 776 000 (Hz) Ca

- 429 228 004 229 800 (Hz) 800 229 004 228 - 429 55600 55700 55800 55900 56000  71 YY/MM/DD 12/03/14 JILA SYRTE UT-NMIJ PTB NICT Modified Julian Date =11/02/08

Frequency comparison between Ca+ ion clock and Sr lattice clock

)

-15 3 2.41014 /  2 Ca/Sr 10-15 1 = 0.957 631 202 358 049 9 (2 3) 14 0

110 /  -1 2.3e-15 Fractional uncertainty 2.3e-15

Ca+-Sr -2

total uncertainty total uncertainty + Sr interleaved meas. -0.957631202358050 (X10 YY/MM/DD

Sr -3 Evaluation Ca ion clock using  -16 / =11/10/16-11/11/10 12/05/13-12/06/17 Allan standard deviation Allan standard 10 Ca

 55840 55860 55880 56060 56080 56100 100 101 102 103 104 Sr lattice clock as a reference Averaging Time (sec) Modified Julian Date 115In+ single-ion optical clock Cs fountains as PFS

1 CSO Target: P1 NICT-CsF1 (Cryogenic Sapphire Accuracy in the order of 10‐18 3P 2 3P Oscillator) 1 3P New approaches: 159nm 0 + 170MHz Sympathetic cooling with Ca clock Fast state detection 236.5nm 1 0.8Hz ・Simplified quantum logic S0 Copper heat sink Microwave Crimped transmission vacuum seal line Mylar seal ・Direct excitation of VUV transition (159nm) Microwave cable loop Outer can

Vacuum ~10-6 Torr Hybrid clock with the Sr optical lattice clock Inner can NICT-CsF2 (Ca+,In+,Ca+) 1.0 aligning laser 0.8 -3 -2 -1 0 1 2 3 Hz Method for preparing the 0.6 pulse + + +, + + In ‐Ca ion chain in a linear (In Ca ,Ca ) 0.4 trap has been established 0.2 (Ca+,Ca+,In+) (Appl. Phys. B, 107,965(2012) 0.0 -150 -100 -50 0 50 100 150 The clock laser system with Hz‐order linewidth is ready Frequency - 9192631770 Hz 12 accuracy evaluation campaigns have been reported Vacuum Chamber λ/4 to BIPM since 2006.

ULE M Cavity Cs‐F2 based on optical molasses is under development.

PD ● ● ● ● PD DBM 15MHz NICT-CsF1 – SI second on the geoid

Servo -15 10 Master PBS ECDL EOM M Single Mode Fiber (2m) -15 946nm >500mW 10 5 25mW tapered amplifier 0

237nm PPKTP 473nm BBO >100mW >10mW -5 Frequency difference / / difference Frequency

The first clock operation is planned in FY2013 -10 Frequency difference / 10 / difference Frequency with an initial accuracy of 10‐14 53800 54000 54200 54400 54600 54800 55000 55200 55400 55600 YY/MM/DD =06/03/06 MJD 11/02/08 Optical fiber link between NICT and UT Carrier phase TWSTFT TWSTFT UT Beat NICT Code DPN方式 (NICT-TL(台湾)) [1] -10 TWSTFT CP [2] 0‐10 measur 10 従来方式: TWSTFT Code ement GPS CP MDEV

(GPS CP)-(TWSTFT CP) ‐011-11 10 予想される水素メーザー原子時計の安定度 in

769nm ‐12-12 769nm 100 698 nm ‐13-13 698 nm x2 x2 100 stability

1.5μm 10‐014-14 Optical TWSTFT CP Sr ‐15-15 carrier Sr 100 60 km link transfer -16 system Frequency ‐016 10 0 1 2 平均化時間3 [秒] 4 5 6 100 1010 1 1010 2 10103 1010 4 1010 5 1010 6 * All optical link system achieved 2e‐15 @ 1 s Averaging time (sec) and 7e‐17 @ 1000 s. * Operational carrier phase TWSTFT via a * 2 remote Sr lattice clocks agreed in 10‐16 level. geostationary satellite was demonstrated * Frequency shift of 2.6 Hz attributed in in 150‐km baseline for the first time. elevation difference of 56 m was detected * Measurement precision of 0.4 ps was achieved. after 10 s average. ( 1000 times better than conventional TWSTFT.) * Common‐clock measurement: 20 15 2e‐13@1s 10 1e‐15@4000s 1e‐1310 -13 5 are achieved. 10 -14 0

-5 * This is comparable to 10 -15 MDEV -10 Sr(NICT)‐Sr(UT) inter‐continental 10 -16 Frequency difference [Hz] difference Frequency -15 wo/ systematic correction ACES MWL. 1e‐15@4000s -20 10 -17 0 1000 2000 3000 4000 5000 6000 7000 8000 10 0 10 1 10 2 10 3 10 4 10 5 time [s] SLR station in NICT •Koganei (7308): Optical Communication Ground Station since 1990.  Telescope Aperture: 1.5 m  Laser :532 nm 50 mJ 20 Hz, 50ps pulse width  UTC(NICT) signal has been provided through optical fibers since 2009. •Koganei (7308) joined the T2L2 campaign in October 2009. •The laser will be renewed in 2014. FrequencyFrequency transfer transfer stability stability with DORISwith DORIS •Operation continuity of the telescope 10‐1010-10 NICT is under discussion. OCA

-11 10‐1011 Deviation

Allan

-12 Modified Allan deviation Modified Allan ‐1012 10 2009/10/15

Modified 2009/10/13

10‐1013-13 1110100 10 100 AveragingAveraging time time [s] (sec) Weather condition in Tokyo

Year: 1980 ~ 2010 Month Ratio [%] 100100 174 268 8080 355 457 6060 550 [%] 636 739 4040 Ratio 853 939 2020 10 48 11 58 0 123456789101112Year 12 73 1 2 3 4 5 6 7 8 9 10 11 12 Year Year 54 MonthMonth

・Ratio of number of days for actual sunshine duration > 40 %. ・Reference: Japan Meteorological Agency,

http://www.data.jma.go.jp/obd/stats/etrn/view/nml_sfc_ym.php?prec_no=44&block_no=47662&year=&month=&day= &view=a4 Agenda

• Background • Report from o University of Tokyo and RIKEN o NMIJ o NICT • Summary of activities in 4 institutes • Summary Summary of atomic clocks

Site Atomic clocks including under development

NMIJ Yb lattice clock Sr‐Yb lattice clock NMIJ‐F1 NMIJ‐F2 NICT 87Sr lattice clock Ca+ single ion clock In+ single ion clock NICT‐CsF1 NICT‐CsF2 UT & RIKEN 3 87Sr lattice clocks (1 in UT, 2 in RIKEN) 2 Hg lattice clocks (2 in RIKEN)

Total 4 Cs fountains 2 single ion clocks 8 optical lattice clocks Summary of frequency links

NMIJ

Japan RIKEN Standard Time NICT

UT

4 institutes can be linked by fiber links or satellite links. Summary

• Various optical clocks are being developed at 4 institutes (NMIJ, NICT, Univ. Tokyo and Riken) around Tokyo area.

• These institutes can be linked by optical fiber or satellites, and collaborate together to join ACES (If its ground terminal comes to Japan).