Status Report on Time and Frequency Activities at

Status Report on Time and Frequency Activities at NPL India (APMP -TCTF 2012) A. Sen Gupta, A. Chatterjee, A. K. Suri, A. Agarwal, S. Panja, P. Arora, S. Yadav, P. Kandpal, M. P. Olaniya (Wellington – Nov 2012) 1

Major activities Time and Frequency Metrology – Generation of UTC(NPLI) – BIPM Link using GNSS – BIPM Link using TWSTFT Cs Fountain Frequency Standard – Evaluation of the first Cs Fountain – in progress. – Design and development of the second Cs Fountain. Time Dissemination – Dissemination by Telephone Time broadcast (Teleclock), and NTP server. Calibrations – Atomic Clocks (Rb & Cs Freq Standards), Time Interval Counter, Hour Meter, Teleclocks, GPS timing receivers and Stopwatch. – Providing traceability to IRNSS time scale. Optical Frequency Standards – Plans and initial activity on single trapped Yb+ ion standard.

IN MHM 2010 1 PPS IN Ф resolution= 2π(2 -32)rad. Freq. Resolution = 5 E-19 5 MHz out Distribution Amplifier-1 Micro Phase Stepper out 1 PPS 5 MHz out Hydrogen Maser HM 1 5 MHz To Calibration Lab FREQUENCY DOUBLER UTC(NPLI) 1 PPS Cs Clock 2 10 MHz To Fountain Lab 1 PPS 5 MHz Schematics of Generation of UTC(NPLI)- 1 1 PPS Cs Clock 3 1 PPS 5071 A-C 001 Cs Clock 6 1 PPS 5071 A-C 001 1 PPS Cs Clock 7 5071 A-C 001 Cs Clock 8 5071 A-C 001 1 PPS 5071 A-C 001 1 4 Automatic 2 3 Switching Unit 6 7 5 START STOP Time interval counter 1 (25 psec resolution) ----------- @ Controller Workstation To Satellite Links

5 MHz Cs Clock 3 5 MHz 1 PPS 5071 A-C 001 Cs Clock 6 5 MHz 5071 A-C 001 1 PPS out ----------- 5 MHz Multi-Channel DMTD Phase Comparator @ Controller Workstation IN Micro Phase Stepper(Aux) out 5071 A-C 001 Freq. Resolution = 5 E-19 UTC(NPLI) 5 MHz Cs Clock 2 IN Ф resolution= 2π(2 -32)rad. FREQUENCY DOUBLER 5 MHz UTC(NPLI) - Aux To Satellite Links 1 PPS 5 MHz Cs Clock 7 5071 A-C 001 Cs Clock 8 5071 A-C 001 5 MHz 10 MHz MHM 2010 1 PPS out IN 5 MHz out 1 PPS 5 MHz out Distribution Amplifier-1 Micro Phase Stepper out Hydrogen Maser HM 1 5 MHz 1 PPS To Fountain Lab To Calibration Lab 1 PPS 5 MHz Schematics of Generation of UTC(NPLI)- 2 ----------- @

Photograph of the Clock Setup at NPLI

Schematics of GNSS and TWSTFT Links Pik Time TTS 2 A Sngl Freq GPS Rx Pik time TTS 4 Dual Freq GPS Rx Pola. Rx 3 e. TR Dual Freq GPS Rx TWSTFT SATRE MODEM Antenna Control unit @ 1 PPS Workstation for controlling ----SATRE -----MODEM ----operation 10 MHz Beacon Receiver 10 MHz 1 PPS Distribution Amplifier-2 10 MHz Saw Filter 2. 5 MHz Data ----------- @ Workstation for controlling GPS Rx operation 1 PPS

Photographs of GNSS and TWSTFT Links

UTC(NPLI)-UTC(PTB), ns Typical GPS P 3 Link Results MJD σ = 1. 2 ns

UTC(NPLI)-UTC(PTB), ns Typical GPS Carrier Phase PPP Results MJD σ = 0. 030 ns Using NRCAN PPP Software developed by Dept of Naural Resources, Canada

UTC(NPLI)-UTC(PTB), ns Typical TWSTFT Results on the Eu-Asia Network MJD σ = 0. 309 ns

UTC - UTC(NPLI) from BIPM Circ-T UTCr - UTC(NPLI) – BIPM Pilot Expt

First Cs Fountain (India-Cs. F 1) Front View 490 2 x 55 l/s Ion Pumps Cs Free Flight UHV Chamber 300 236. 125 150 972 3 Layers of Magnetic shields C-Field Solenoid Microwave Cavities Detection Zone 400 Octagonal MOT Chamber 2 x 20 l/s Ion Pumps 850 India Cs-F 1 is fully Operational and is presently being evaluated

India-Cs. F 1 – Typical Results Effect Bias (x 10 -15) Uncertainty (x 10 -15) 2 nd order Zeeman 50. 8 0. 1 AC Stark (BBR) -16. 5 0. 2 Collisions * 1. 0 (approx) Gravity 19. 4 0. 1 Other effects * 0. 1 (approx) Total, u. B * to be evaluated 1. 0 (utotal)2 = (u. A)2+(u. B)2+(ulink/lab)2

Second Cs Fountain (India-Cs. F 2) • (1, 1, 1) geometry for cooling and launching • Two coils in anti-Helmholtz configuration • Three pairs of rectangular Helmholtz coils • Two detection beams of 10 mm x 10 mm • Optical pumping to enhance the mf = 0 population

Time Dissemination Teleclock Service Internet Time Service Domain name: time. npli. in

Calibration Services We are providing UTC Traceability to the Time scale of the Indian Regional Navigational Satellite System (IRNSS). This Time scale is known as the IRNWT and is maintained by the Indian Space Research Organization (ISRO). The technique used presently is all in view GPS P 3. We are planning to supplement this with a dedicated TWSTFT link. We are providing Time & Frequency in house Calibration Services to Test & Calibration Labs from Govt. and Industries for the calibration of Rb & Cs Atomic Clocks, Time Interval Counters, Hour meters, Teleclocks, GPS receivers and Stop watches

New Developments We have just received funding to start work on a Single Trapped Ion Optical Frequency Standard. We plan to work on Yb+ ions. We plan to move some our activities to the New Metrology Building next year.

Thank You for your Attention