Measurements and Distribution: PNT and Other Applications

Transcription

1 NIST Time and Frequency Metrology Precision Time and Frequency Measurements and Distribution: PNT and Other Applications Tom O Brian Chief, NIST Time and Frequency Division and NIST Quantum Physics Division (JILA) Boulder, Colorado

2 NIST Time and Frequency Metrology, Boulder, Colorado PNT tf.nist.gov g jila.colorado.edu

3 NIST Time and Frequency Metrology, Boulder, Colorado Research, standards, and dissemination for precision timing and synchronization. tf.nist.gov jila.colorado.edu

4 NIST-F1 Atomic Fountain Clock Primary Frequency Standard for the United States 1 second is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the 133 Cs atom. Current accuracy (uncertainty): 3 x second. 25 trillionths of a second per day. NIST-F1 laser-cooled cesium fountain frequency standard d atomic clock 1 second in 100 million years. Equivalent to measuring earth-sun distance (150,000,000 km) to uncertainty of about 45 m (less than thickness of human hair).

5 NIST Mercury Ion Clock and Aluminum Ion Logic Clock Research Frequency Standards Research atomic clocks at NIST already at 8 x uncertainty. 1 second in 4 billion years. Rapidly improving. Equivalent to measuring earth-sun distance (150,000,000 km) to uncertainty of about 1 m (size of a bacterium). Why worry about precision time and frequency metrology?

6 Impacts of Precise Timing and Synchronization Telecommunication Networks Synchronization to about 1 microsecond per day (10-11 ) for Stratum 1 telecommunications. Global wireline and wireless revenue in 2007: $1.65 trillion. Projected global wireline and wireless revenue in 2012: $2.3 trillion. (2/3 of projected 2012 revenue in wireless systems) Source: Verizon

7 Impacts of Precise Timing and Synchronization Electric Power Generation and Distribution Synchronization to about 1 microsecond per day (10-11 ) for efficiency, fault location, etc. US electric power sales in 2008: $360 billion. Smart Grid: Increased need for real-time, precision information on electric power generation, utilization, and distribution. Source: US Energy Information Administration

8 Broad Range of Civilian/Commercial Global Navigation Satellite Systems Applications Satellite Operations Aviation Precision Agriculture Surveying & Mapping Communications Disease Control Power Grids Trucking & Shipping Personal Navigation Oil Exploration Fishing & Boating

9 Impacts of Precise Timing and Synchronization Global Navigation Satellite Systems (GNSS) Civilian/commercial economic benefits estimated 2008: US: $70 billion Global: $250 billion New applications and impacts rapidly growing National security applications: Priceless Source: US National Executive Committee for Space-Based Positioning, Navigation, and Timing

10 Impacts of Precise Timing and Synchronization Electronic Financial Transactions US Financial Industry Regulatory Authority (FINRA) rules for electronic financial transactions, reviewed and approved by US Securities Exchange Commission. Rules apply to more than 800,000 businesses conducting billions of transactions daily through New York Stock Exchange, NASDAQ, and other venues. All FINRA member electronic and mechanical time-stamping devices must remain accurate to within 1 second of NIST time. Hundreds of billions of dollars of daily electronic financial transactions in US. Hundreds of trillions of dollars of financial transactions per year in US. Source: US Financial Industry Regulatory Authority

11 Impacts of Precise Timing and Synchronization Science: Spacecraft Communications, Astrophysics Very Long Baseline Interferometry t Timing/synchronization to as stringent as 1 picosecond per day (10-16 ). NASA Deep Space Network Source: NASA

12 Impacts of Precise Timing and Synchronization Fundamental Science T T 2 0 T ( 1 ) v c 2 v 2 c v c T 0 T 0 ( 1 ) 2 2 c 1 T 2 GM 2 Rc Special and General Relativity and related phenomena GM Rc 2 GM R Time-evolution of fundamental constants? Superluminal neutrinos?

13 Impacts of Precise Timing and Synchronization Fundamental Metrology: International System of Units (SI) Time/frequency impacts or will impact nearly all other SI units SI Base Unit Approximate Uncertainty in Current Realization Currently Depends on SI Second Proposed SI Redefinition 2014 Second Yes (no change) Meter Yes c (m / s) (no change) Kilogram 10-9 h (J s) Ampere 10-7 Yes e (A s) Mole 10-7 N A Kelvin 10-7 k (kg m 2 / s 2 / K) Candela 10-3 Yes K cd (cd sr s 3 / kg / m 2 )

14 Impacts of Precise Timing and Synchronization Precise timing and synchronization are a crucial part of the infrastructure of modern technology. Used continuously every day although h most users remain unaware of the use or impacts (part of the infrastructure). Needs of different users vary enormously range of (fifteen orders of magnitude). Timestamping of electronic financial transactions 1 second precision. Global Navigation Satellite Systems applications second precision. NIST and other National Metrology Labs provide broad range of timing and synchronization measurement services to meet this very broad range of needs. Highest precision/accuracy for the most stringent requirements. Easiest use/lowest cost (free) for the broadest applications.

15 Improvements in Primary Frequency Standards Freque ency Unc certainty NBS Years of NBS-2 Progress in Atomic Clocks NBS-3 NBS-5 NBS-4 NBS-6 NIST-F1 Initial NIST-7 NIST-F1 Today Why Improve Primary Frequency Standards? Year

16 Improvements in Primary Frequency Standards NBS Needs as Deployed Stratum 1 Telecomm Freque ency Unc certainty VLBI/Deep Space/ Current GNSS Future GNSS Current NIST-F VLBI/Deep Space/Gravimetry, etc. Future Year

17 Improvements in Primary Frequency Standards Freque ency Unc certainty NBS VLBI/Deep Space/ Current Needs with Conservative Calibration Uncertainty GNSS Future Stratum 1 Telecomm GNSS Current NIST-F VLBI/Deep Space/Gravimetry, etc. Future Year

18 NIST Time and Frequency Standards and Distribution Primary Frequency Standard and NIST Time Scale Realization of SI second NIST-F1 Hydrogen Maser & Measurement system

19 NIST Time and Frequency Standards and Distribution Time and Frequency Distribution Services Radio broadcasts Networks Satellites Noise metrology Primary Frequency Standard and NIST Time Scale Realization of SI second NIST-F1 Hydrogen Maser & Measurement system

20 NIST Time and Frequency Standards and Distribution Time and Frequency Distribution Services Radio broadcasts Networks Satellites Noise metrology Primary Frequency Standard and NIST Time Scale Realization of SI second NIST-F1 Hydrogen Maser & Measurement system Research on Future Standards d and Distribution Mercury ion clock Neutral calcium clock Optical frequency synthesis Quantum computing

21 NIST Time and Frequency Standards and Distribution Time and Frequency Distribution Services Radio broadcasts Networks Satellites Noise metrology Primary Frequency Standard and NIST Time Scale Realization of SI second NIST-F1 Hydrogen Maser & Measurement system Research on Future Standards d and Distribution Mercury ion clock Neutral calcium clock Optical frequency synthesis Quantum computing

22 NIST Time Scale and Distribution Cesium Beam Standards Two-way satellite time & frequency transfer UTC(NIST) Hydrogen Masers GPS Measurement System Calibrated by NIST-F1 primary frequency standard International coordination of time and frequency: UTC, TAI, etc.

23 NIST Time and Frequency Metrology NIST-F1 primary frequency standard periodically calibrates NIST time scale. NIST-F1 also reports frequency information to BIPM, along with approximately 12 other primary frequency standards worldwide. NIST time scale is the source of NIST s realization of Coordinated Universal Time, UTC(NIST). NIST time scale reports time of day information to BIPM, along with approximately 60 other timing laboratories world-wide. The NIST time scale periodically calibrated by NIST-F1 is the The NIST time scale, periodically calibrated by NIST-F1, is the ultimate source of all NIST time and frequency measurements.

24 UTC, Coordinated Universal Time. Time Scales Maintained by International Bureau of Weights and Measures (BIPM). Based on input from ~60 timing labs world-wide. ~400 atomic clocks total. Post-processed paper time scale. Published monthly. Data are approximately 2 weeks to 6 weeks old. Local realizations/estimates of UTC. UTC(lab) local estimate/realization of UTC. Usually real-time or near-real-time estimate. UTC(NIST) real time estimate of UTC. UTC(USNO) real time estimate of UTC. GPS estimate of UTC. Very close (but not identical) to UTC(USNO).

25 NIST Time and Frequency Distribution GPS UTC(NIST) T ~ ± 10 ns UTC(NIST) compared to GPS time (GPS estimate of UTC) over 10 days. GPS estimate of UTC is very close to UTC(USNO).

26 NIST Time and Frequency Distribution GPS UTC(NIST) T ~ ± 10 ns UTC(NIST) compared to GPS time (GPS estimate of UTC) over 200 days. GPS estimate of UTC is very close to UTC(USNO).

27 NIST Time and Frequency Distribution 8 6 UTC(USNO) - GPS 4 Nanose econds T ~ ± 5 ns Days UTC(USNO) compared to GPS time (GPS estimate of UTC) over 180 days.

28 NIST Time and Frequency Distribution NIST DO UTC(NIST) By Common-View GPS T ~ ± 0.5 ns UTC(NIST) compared to NIST-Disciplined Oscillator linked to UTC(NIST) by Common View GPS. 100 days of data.

29 NIST Time and Frequency Distribution Serve the most demanding needs of timing laboratories, research laboratories, telecomm industry, etc. Provided remotely in the customer s s lab. Global Time Service Calibrate remote clock with respect to NIST time via Common-View GPS. 10 ns uncertainty. Frequency Measurement and Analysis Service Full measurement system ( black box ) with continuous remote monitoring by NIST. In-house f/f ~ 2 x GPS transfer f/f ~ 2 x

30 SIM Time Network: International Time Coordination SIM Time Network. Pioneered by CENAM, NIST, NRC-Canada. Based on NIST FMAS experience. 14 current partners in North, Central, and South America. Additional partners planned. World s only near real-time international measurement system. World class international measurement system World-class international measurement system available to broad range of national laboratories.

31 SIM Time Network: International Time Coordination Real-time Comparison of NIST (USA) and CENAM (Mexico) Time Scales through SIM Network Circular T data = BIPM realization of UTC Real-time international time scale competitive with post-processed BIPM UTC realization (up to several weeks late) with much simpler and less-expensive equipment.

32 NIST Time and Frequency Distribution f Daily Synchs Billions of NIST Internet Time Service time codes delivered d over the Internet t via NTP (and other protocols). 8 billion automated synchs per day. Built into common operating systems: Windows, Mac, Linux, etc. 23 servers at 19 locations across the US. Expected significant growth in need for auditable time-stamping at ever greater timing precision. NY Stock Exchange NY Stock Exchange Automated Trading Anomaly May 6, 2010

33 NIST Time and Frequency Distribution Network Time Protocol (NTP). Computers exchange two-way messages over public or private network. Measures round-trip network delay. Algorithms for disciplining the system clock, choosing optimal query interval, etc. Performance depends on symmetry of path delay. Almost always better than 50 ms performance. Usually better than 10 ms performance. Best case for distributed public network ~0.5 ms performance. ~ 1 s for limited private network under ideal conditions.

34 NIST Time and Frequency Distribution Precision Time Protocol (PTP). IEEE Master/Slave timing. Multiple boundary clocks. Designed for sub-nanosecond timing, frequency stability.

35 NIST Time and Frequency Distribution Actual PTP performance. 4 different equipment manufacturers.

36 NIST Time and Frequency Standards and Distribution Time and Frequency Distribution Services Radio broadcasts Networks Satellites Noise metrology Primary Frequency Standard and NIST Time Scale Realization of SI second NIST-F1 Hydrogen Maser & Measurement system Research on Future Standards d and Distribution Mercury ion clock Neutral calcium clock Optical frequency synthesis Quantum computing

37 NIST-F1 Primary Frequency Standard 0-15 f/f x NIST-F1 Frequency Uncertainty (In House) Formal Evaluations reported to BIPM since Dec Dec Dec Modified Julian Date NIST-F1 1Cesium Fountain Standard 0.3 x in house frequency uncertainty. 0.6 x frequency uncertainty reported to BIPM.

38 Improvements in Primary Frequency Standards NBS Freque ency Unc certainty NIST-F1 NIST-F2 Beyond Cesium? Year

39 Improvements in Primary Frequency Standards Frequency uncertainty ~ f 1 1 f N 0 f 15 f optical f0 microwave 10 5 Atomic Resonance = observation time N = number of atoms NIST research atomic clocks Al THz (1124 x Hz) Hg THz Yb 520 THz Optical Ca 456 THz Sr 430 THz Cs THz Microwave

40 Ultrastable Lasers Q = 3 x 1015 Miniature ultrastable cavity Spectral hole burning Potential for Q ~ 1017

41 Femtosecond Laser Frequency Combs: Key to Optical Clocks

42 Laser Frequency Comb: Gears of the Optical Clock Frequency Comb 10 5 :1 Reduction Stable Laser Optical Frequency ~10 15 Hz Not to Scale! Microwave Standards or Sources Hz

43 Femtosecond Laser Frequency Combs: Key to Optical Clocks Optical ref 1 fs laser Optical ref Compare 1 vs 2 Optical reference 1 set n = opt m - opt2 Optical reference 2 0 Optical standards at NIST Al + (1124 THz), Hg + (1064 THz), neutral Yb (520 THz) and Ca (456 THz) x 2 set f o = 0 Direct comparison to Cs ( THz)

44 Improvements in Primary Frequency Standards: Optical Clocks NBS-1 Optical Frequency Standards (Research) rtainty Freque ency Unce Cesium Microwave Primary Frequency Standards d NIST-F NIST optical clocks Year

45 Optical Frequency Standards Frequency uncertainty ~ Perturbations: Dephasing collisions. Blackbody radiation. f 1 1 b ti ti f N 0 Magnetic fields. Etc. = observation time N = number of atoms Single Ions Large Rare collisions Well-controlled environment Cold Neutral Atoms Large N Lattices to minimize collisions i More complex environment

46 NIST Single Ion Optical Frequency Standards ~8 x Al + quantum logic optical clock. Single Hg+ ion Single mercury ion trap. ~1 x 10-17

47 NIST Aluminum Ion Logic Clock Al + Be + Linear Paul Trap 1. Cool to zero-motion quantum state with Be Depending on clock state, add vibrational energy via Al Detect vibrational energy via Be Al + 1 S 0 Mean = Al + 3 P 0 Mean = 6.9 Pro obability Probability % Detection fidelity PMT counts Be + photon counts

48 Al + clock gravitational shift f/f = 8 x Gravitational frequency shift near Earth surface ~1 x / cm

49 Al + clock gravitational shift Measure frequency shift by raising clock as little as 10 cm. Measure frequency shift by moving Al + ion as slowly as jogging speed (about 3 m/second). Extreme precision optical clocks may initially be most useful as exquisitely precise atomic sensors: Gravity. Magnetic fields. Acceleration. Temperature. Other quantities

50 NIST Optical Frequency Standards Optical Lattice Clocks Ytterbium (NIST) Strontium (JILA) ~1 x 10-17, rapidly improving

51 Improvements in Primary Frequency Standards: Optical Clocks NBS-1 Optical Frequency Standards (Research) rtainty Freque ency Unce Best NIST-F Future NIST optical clocks Clock??? Year

52 Improvements in Frequency Standards and Clocks NIST-F clocks (0.1/month) clocks (10/month) clocks (1,000/month) 10-9 clocks (100,000/month) Master clocks (long term synchronization) Secure communications Deep space navigation GPS Master clock (ground) Large scale communications systems Power grids GPS Space Clocks Local synchronization Local communications hubs Instrumentation level flywheels Short haul navigation Local communications Opportunities for Improvement?

53 NIST Chip-Scale Atomic Devices Sensors Based on Atomic Frequency Metrology 1 mm Chip-scale atomic clock Chip-scale atomic magnetometer Ultraminiature gyroscope Future atom-based sensors

54 NIST Chip-Scale Atomic Devices Pea Chip-scale atomic clock Chip-scale atomic clocks: f/f or better. <100 mw power consumption. Potential for low-cost mass production. Chip-scale atomic magnetometers: sensitivity: SQUID performance with no cryogens. Ultraminiature NMR gyroscopes: Navigation grade (0.002 degree). Ultraminiature spectrometer Related devices: Ultraminiature spectrometer for telecommunications, chemical identification, atmospheric research, etc. NIST chip-scale atomic device program since August 2004: Several NIST patents. More than 100 NIST publications on chip-scale atomic devices. Dozens of conference and workshop presentations.

55 Commercialization of Chip-Scale Atomic Devices Symmetricom Chip-Scale Atomic Clock First commercial chip-scale atomic device Introduced January 2011 Other commercial products in development by several companies

56 y ( ) Research on Ultraminiature Cold Atom Clocks 10-9 CSAC Aims to exceed Cesium beam clock performance for 1000 lower power z IMPACT and size. CSAC Block IIR RAFS A Beam Clock 5071A Block IIR RAFS DARPA IMPACT Goals Power Size Timing Uncertainty < 50 mw 5 cc (total) 5 1 day IMPACT t (s) Sandia/JPL: OEWaves/Aerospace: Honeywell: Symmetricom: NIST: Trapped 171 Yb ions Kerr optical frequency combs Laser-cooled Rb, microwave interrogation Laser-cooled Rb, CPT interrogation

57 Research on Cold Atom GPS Clock Source State Selection Dielectric Loaded Ramsey Cavity Detection Approximately same size as current GPS RAFS

58 Improvements in Time and Frequency Distribution Ion Optical Clocks Fiber Distribution Systems Future optical clocks f/f ~ 1x10-18 Frequency Combs High accuracy. Direct reference of optical applications to optical standards. New applications. Directly compare optical frequencies spanning more than an octave. Link optical to microwave frequencies. Optical Satellite Distribution Crucial topic For another talk.

59 NIST Fiber Optic Time and Frequency Transfer

60 tf.nist.gov

61 Public, searchable database of Time & Frequency Division publications. tf.nist.gov t >2,500 PDFs posted.

62 Time and Frequency Research and Metrology in Boulder JILA NIST Boulder