Precision Time and Frequency Measurements and...
Transcript of Precision Time and Frequency Measurements and...
NIST Time and Frequency MetrologyNIST Time and Frequency Metrology
Precision Time and FrequencyPrecision Time and FrequencyMeasurements and Distribution:
PNT and Other ApplicationsMeasurements and Distribution:
PNT and Other ApplicationsPNT and Other Applications
T O’B i
PNT and Other Applications
T O’B iTom O’BrianChief, NIST Time and Frequency Division
and NIST Quantum Physics Division (JILA)
Tom O’BrianChief, NIST Time and Frequency Division
and NIST Quantum Physics Division (JILA)and NIST Quantum Physics Division (JILA)Boulder, Colorado
and NIST Quantum Physics Division (JILA)Boulder, Colorado
NIST Time and Frequency Metrology, Boulder, Colorado
PNTPNTtf.nist.govg
jila.colorado.edu
NIST Time and Frequency Metrology, Boulder, Colorado
Research, standards, and dissemination for precision timing
d h i ti
tf.nist.gov
and synchronization.
gjila.colorado.edu
NIST-F1 Atomic Fountain ClockPrimary 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 gtransition between the two hyperfine levels of the ground state of the 133Cs atom.”
Current accuracy (uncertainty):
• 3 x 10-16 second.
NIST-F1 laser-cooled cesium f t i f t d d
• 25 trillionths of a second per day.
• 1 second in 100 million years.
fountain frequency standard“atomic clock”
Equivalent to measuring earth-sun distance (150,000,000 km) to uncertainty of about 45 m (less than thickness of human hair).
NIST Mercury Ion Clock and Aluminum Ion Logic ClockResearch Frequency Standards
• Research atomic clocks at NIST already at 8 x 10-18 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?
Impacts of Precise Timing and Synchronization
Telecommunication Networks
Synchronization to about 1 microsecond per day (10-11) for Stratum 1 telecommunicationstelecommunications.
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
Electric Power Generation and Distribution
Impacts of Precise Timing and Synchronization
Synchronization to about 1 microsecond per day (10-11) for efficiency, fault location, etc.
US electric power sales in 2008: $360 billion.p $Smart Grid: Increased need for real-time, precision information on electric power generation, utilization, and distribution.
Source: US Energy Information Administration
Broad Range of Civilian/Commercial Global Navigation Satellite Systems Applications
SatelliteOperations
SatelliteOperations
AviationAviation
Surveying & MappingSurveying & MappingPrecision AgriculturePrecision Agriculture
CommunicationsCommunications
Power GridsPower GridsDisease ControlDisease Control
Personal NavigationPersonal Navigation
Trucking & Shipping
Trucking & Shipping
NavigationNavigation
Fishing &BoatingFishing &BoatingOil ExplorationOil Exploration
Global Navigation Satellite Systems (GNSS)
Impacts of Precise Timing and Synchronization
g y ( )
Civilian/commercial economic benefitsCivilian/commercial economic benefits estimated 2008:
US: $70 billionGlobal: $250 billion
New applications and impacts rapidly growing…growing…
N ti l it li ti “P i l ”National security applications: “Priceless”
Source: US National Executive Committee for Space-Based Positioning, Navigation, and Timing
Electronic Financial Transactions
Impacts of Precise Timing and Synchronization
• US Financial Industry Regulatory Authority (FINRA) rules for electronic financial transactions, reviewed and approved by US Securities Exchange Commission.pp y g
• 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 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
Science: Spacecraft Communications, Astrophysics
Impacts of Precise Timing and Synchronization
V L B li I t f tVery Long Baseline Interferometry
Timing/synchronization to asTiming/synchronization to as stringent as 1 picosecond per day (10-16).
NASA Deep Space Network
Source: NASA
Fundamental ScienceImpacts of Precise Timing and Synchronization
2
0
21RcGM
TT
)1( 20 Rc
GMT 22 cR
GM
2
2
0
1 v
TT
)2
1( 2
2
0 cvT cv
2c
Special and General Relativity and related phenomena…
Time-evolution of fundamental “constants”?
Superluminal neutrinos?
Fundamental Metrology: International System of Units (SI)Ti /f i t ill i t l ll th SI it
Impacts of Precise Timing and Synchronization
SI Base Unit Approximate Uncertainty in
Currently Depends on SI
Proposed SI Redefinition
Time/frequency impacts or will impact nearly all other SI units
Uncertainty in Current
Realization
Depends on SI Second
Redefinition2014
Second 10-15 Yes (no change)Second 10 Yes (no change)
Meter 10-12 Yes c (m / s) (no change)
Kilogram 10-9 h (J s)
Ampere 10-7 Yes e (A s)
Mole 10-7 NA
Kelvin 10-7 k (kg m2 / s2 / K)
Candela 10-3 Yes Kcd
(cd sr s3 / kg / m2)
• Precise timing and synchronization are a crucial part of the infrastructure of
Impacts of Precise Timing and Synchronization
Precise timing and synchronization are a crucial part of the infrastructure of modern technology.
U d ti l d lth h t i f th• Used continuously every day – although most users remain unaware of the use or impacts (part of the infrastructure).
• Needs of different users vary enormously – range of 1015 (fifteen orders of magnitude).
• Timestamping of electronic financial transactions – 1 second precision.p g p
• Global Navigation Satellite Systems applications – 10-15 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.
Improvements in Primary Frequency Standards10-9 10-910
10-10
10-11
10-10
10-11
NBS-160 Years of Progress in
Atomic ClocksNBS-2
10-12
10-13
10-12
10-13certa
inty
Atomic Clocks
NBS-5
NBS-4NBS-3
10
10-14
15
10
10-14
15ency
Unc
NIST-7NBS-6
NBS-5
10-15
10-16
10-15
10-16Freq
ue
NIST-F1Today
NIST-F1Initial
10-17
10-18
10-17
10-18
Why Improve Primary Frequency Standards?
1940 1950 1960 1970 1980 1990 2000 2010 2020Year
Improvements in Primary Frequency Standards10-9 10-910
10-10
10-11
10-10
10-11Stratum 1 Telecomm
Needs as DeployedNBS-1
10-12
10-13
10-12
10-13certa
inty
10
10-14
15
10
10-14
15ency
Unc GNSS Current
GNSS Future10-15
10-16
10-15
10-16Freq
ue
VLBI/Deep Space/ Current NIST-F1
10-17
10-18
10-17
10-18
VLBI/Deep Space/Gravimetry, etc. Future
1940 1950 1960 1970 1980 1990 2000 2010 2020Year
Improvements in Primary Frequency Standards10-9 10-910
10-10
10-11
10-10
10-11
Needs with ConservativeCalibration Uncertainty
NBS-1
10-12
10-13
10-12
10-13certa
inty Stratum 1 Telecomm
10
10-14
15
10
10-14
15ency
Unc
GNSS Current10-15
10-16
10-15
10-16Freq
ue
VLBI/Deep Space/ Current
GNSS Future NIST-F1
10-17
10-18
10-17
10-18
VLBI/Deep Space/ Current
VLBI/Deep Space/Gravimetry, etc. Future
1940 1950 1960 1970 1980 1990 2000 2010 2020Year
NIST Time and Frequency Standards and Distribution
Primary Frequency Standard andNIST Time ScaleNIST Time ScaleRealization of SI second
NIST-F1Hydrogen Maser &Measurement system
Time and
NIST Time and Frequency Standards and Distribution
Frequency Distribution Services
Radio broadcasts Networks Satellites Noise metrology
Primary Frequency Standard andNIST Time ScaleNIST Time ScaleRealization of SI second
NIST-F1Hydrogen Maser &Measurement system
Time and
NIST Time and Frequency Standards and Distribution
Frequency Distribution Services
Radio broadcasts Networks Satellites Noise metrology
Primary Frequency Standard andNIST Time Scale
NIST-F1Hydrogen Maser &Measurement system
Realization of SI second
Research on Future St d dStandards and Distribution Mercury ion clock Neutral calcium
clockOptical frequency
synthesisQuantum computing
Time and
NIST Time and Frequency Standards and Distribution
Frequency Distribution Services
Radio broadcasts Networks Satellites Noise metrology
Primary Frequency Standard andNIST Time Scale
NIST-F1Hydrogen Maser &Measurement system
Realization of SI second
Research on Future St d dStandards and Distribution Mercury ion clock Neutral calcium
clockOptical frequency
synthesisQuantum computing
Two-way satellite time
NIST Time Scale and Distribution
Cesium Beam StandardsTwo-way satellite time & frequency transfer
H d M
UTC(NIST)
Hydrogen Masers
GPS
Measurement System
Calibrated by NIST-F1 primary frequency standard
International coordination of time and frequency: UTC, TAI, etc.
NIST Time and Frequency Metrology• NIST-F1 primary frequency standard periodically calibrates NIST time p y q y p y
scale.
• NIST-F1 also reports frequency information to BIPM, along with approximately 12 other primary frequency standards worldwide.pp y p y q y
• 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 p yBIPM, 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.
• UTC, Coordinated Universal Time.
Time Scales
UTC, Coordinated Universal Time.
• 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• 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• UTC(USNO) – real time estimate of UTC.
• GPS estimate of UTC. Very close (but not identical) to UTC(USNO).
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).
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).
8
NIST Time and Frequency Distribution
4
6
8UTC(USNO) - GPS
2
4
econ
ds
-2
0
Nan
ose
-6
-4
T ~ ± 5 ns-8
0 50 100 150 200Days
UTC(USNO) compared to “GPS time” (GPS estimate of UTC) over 180 days.
Days
NIST Time and Frequency Distribution
NIST DO– UTC(NIST)By Common View GPSBy 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.
Serve the most demanding needs of timing
NIST Time and Frequency Distribution
Serve the most demanding needs of timing laboratories, research laboratories, telecomm industry, etc.Provided remotely in the customer’s lab
Global Time Service• Calibrate remote clock with respect to NIST time via
Common View GPS
Provided remotely in the customer s lab.
Common-View GPS.• 10 ns uncertainty.
Frequency Measurement and Analysis Service
F ll (“bl k b ”) i h• Full measurement system (“black box”) with continuous remote monitoring by NIST.
• “In-house” f/f ~ 2 x 10-15.
• GPS transfer f/f ~ 2 x 10-13.
• SIM Time Network.SIM Time Network: International Time Coordination
• Pioneered by CENAM, NIST, NRC-Canada.• Based on NIST FMAS experience.
14 t t i N th C t l d S th• 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.
Real-time Comparison of NIST (USA) and CENAM (Mexico)
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.
• NIST Internet Time Service – time d d li d th I t t
NIST Time and Frequency Distribution10
codes delivered over the Internet via NTP (and other protocols).
• 8 billion automated synchs per day.4
6
8
f Dai
ly S
ynch
s
• Built into common operating systems: Windows, Mac, Linux, etc.
• 23 servers at 19 locations across 0
2
4
Billio
ns o
f
the US.
• Expected significant growth in need for auditable time-stamping at everExpected significant growth in need for auditable time stamping at ever greater timing precision.
NY Stock ExchangeNY Stock ExchangeAutomated Trading AnomalyMay 6, 2010
• Network Time Protocol (NTP).
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 optimalsystem 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.
• Precision Time Protocol (PTP).
NIST Time and Frequency Distribution
Precision Time Protocol (PTP).
• IEEE 1588-2008.
• Master/Slave timing.
• Multiple boundary clocks.
• Designed for sub-nanosecond timing, 10-11 frequency stability.g, q y y
NIST Time and Frequency Distribution
Actual PTP performance. 4 different equipment manufacturers.
Time and
NIST Time and Frequency Standards and Distribution
Frequency Distribution Services
Radio broadcasts Networks Satellites Noise metrology
Primary Frequency Standard andNIST Time Scale
NIST-F1Hydrogen Maser &Measurement system
Realization of SI second
Research on Future St d dStandards and Distribution Mercury ion clock Neutral calcium
clockOptical frequency
synthesisQuantum computing
NIST-F1 Primary Frequency Standard
2.0NIST-F1 Frequency Uncertainty (In House)
1.5
Formal Evaluations reported to BIPM since Dec. 1999.
0-15
1.0
f/f
x 1
S 1 C0.0
0.5
51500 52000 52500 53000 53500 54000 54500 55000
Dec. 1999 Dec. 2009
NIST-F1 Cesium Fountain Standard
• 0.3 x 10-15 in house frequency uncertainty.
51500 52000 52500 53000 53500 54000 54500 55000
Modified Julian Date
q y y• 0.6 x 10-15 frequency uncertainty reported to BIPM.
10-9 10-9
Improvements in Primary Frequency Standards
10-10
10-11
10-10
10-11
NBS-1
10-12
10-13
10-12
10-13
certa
inty
10-14
10-15
10-14
10-15ency
Unc
NIST F110-16
10-17
10-16
10-17
Freq
ue
NIST-F2
NIST-F1
B d C i ?1940 1950 1960 1970 1980 1990 2000 2010 2020
10
10-18
10
10-18Beyond Cesium?
Year
f 11
Improvements in Primary Frequency Standards
Nff 11
0
Frequency uncertainty ~
f
= observation time510
150 10
1010
microwave
opticalf
fAtomic Resonance
N = number of atoms0 10microwavef
NIST research atomic clocks Al+ 1124 THz (1124 x 1012 Hz)Hg+ 1024 THzYb 520 TH OpticalYb 520 THzCa 456 THzSr 430 THz
Optical
Cs 0.0092 THz Microwave
Ultrastable Lasers
Q = 3 x 1015
Miniature ultrastable cavity Spectral hole burning
Potential for Q ~ 1017
Femtosecond Laser Frequency Combs: Key to Optical Clocks
Laser Frequency Comb: “Gears” of the Optical Clock
OpticalFrequency
1015 HStableLaser
Frequency~1015 HzLaserComb
105:1 Reduction
Not toScale!
MicrowaveStandards or Sources
101010 Hz
fs laserOptical ref 1 Optical ref 2
Femtosecond Laser Frequency Combs: Key to Optical Clocks
fs laser1 2
Compare 1 vs 2
Optical
set n = opt
Optical
m - opt2Optical
reference 1Optical
reference 2
0
set fo= 0
x2
Optical standards at NIST
Al+ (1124 THz), Hg+
(1064 THz) neutral Yb(1064 THz), neutral Yb(520 THz) and Ca (456 THz)
Direct comparison to Cs(0.0092 THz)
Improvements in Primary Frequency Standards: Optical Clocks10-9 10-9
10-10
10-11
10-10
10 11
OpticalFrequencyStandards
NBS-1
rtain
ty
10
10-12
10-11
10-12
(Research)
ency
Unc
e 10-13
10-14
10-13
10-14
Cesium MicrowavePrimary FrequencySt d d
Freq
ue
10-15
10-16
10-15
Standards
NIST-F1
10 16
10-17
10-16
10-17
NIST optical clocks
Year1940 1950 1960 1970 1980 1990 2000 2010 2020
10-1810-18
Optical Frequency Standards
f 11 b ti ti
Nff 11
0
Frequency uncertainty ~
= observation time
N = number of atoms
Perturbations:• Dephasing collisions.• Blackbody radiation.
• Magnetic fields.• Etc.y
Single Ions Cold Neutral Atomsg
Large Large N
Rare collisions Lattices to minimize lli icollisions
Well-controlled environment
More complex environment
NIST Single Ion Optical Frequency Standards
~8 x 10~8 x 10--1818~8 x 10~8 x 10--1818
Al+ quantum logic optical clock.
Si l H + iSingle Hg+ ion~1 x 10-17
Single mercury ion trap.
NIST Aluminum Ion “Logic Clock”1 Cool to zero motion quantum state
Be+
Al+
1. Cool to zero-motion quantum state with Be+ .
2. Depending on clock state, add
Linear Paul Trap
vibrational energy via Al+ .
3. Detect vibrational energy via Be+ .
0.6
0.7
0.8
0 1
0.12
0.14
27Al+ 1S0Mean = 1.3
27Al+ 3P0Mean = 6.9
0.4
0.5
Pro
babi
lity
0 06
0.08
0.1
obab
ility
0 1
0.2
0.3P
0.02
0.04
0.06
Pro 99.94% Detection fidelity
0 10 200
0.1
PMT counts0 10 20
0
Be+ photon counts
Al+ clock gravitational shift f/f = 8 x 10-18Al clock gravitational shift
Gravitational frequency shift near Earth surface ~1 x 10-18 / cm
Al+ clock gravitational shiftMeasure frequency shift by raising clock as little as 10 cm.Al clock gravitational shift
Measure frequency shift by moving Al+ ion as slowly asmoving Al+ ion as slowly as jogging speed (about 3 m/second).
Extreme precision optical clocks may initially be most useful asmay initially be most useful as exquisitely precise atomic sensors:• Gravity.• Magnetic fields.• Acceleration.• Temperature.
Oth titi• Other quantities…
NIST Optical Frequency Standards
Optical Lattice ClocksOptical Lattice Clocks
• Ytterbium (NIST)
• Strontium (JILA)
• ~1 x 10-17, rapidly improving
Improvements in Primary Frequency Standards: Optical Clocks10-9 10-9
10-10
10-11
10-10
10 11
OpticalFrequencyStandards
NBS-1
rtain
ty
10
10-12
10-11
10-12
(Research)
ency
Unc
e 10-13
10-14
10-13
10-14
B t
Freq
ue
10-15
10-16
10-15NIST-F1Best
Future10 16
10-17
10-16
10-17
NIST optical clocks
Future Clock???
Year1940 1950 1960 1970 1980 1990 2000 2010 2020
10-1810-18
Improvements in Frequency Standards and Clocks
NIST-F1
10-15 clocks (0.1/month)
10-13 clocks (10/month)
10-9 clocks (100,000/month)
10-11 clocks (1,000/month)
• Master clocks (long term synchronization)
• Secure communications
• Deep space
• Large scale communications systems
• Power grids• GPS Space Clocks
• Local communications hubs• Instrumentation level
flywheels
• Short haul navigation• Local communications
• Deep space navigation
• GPS Master clock (ground)
• GPS Space Clocks• Local synchronization
Opportunities for Improvement?
NIST Chip-Scale Atomic DevicesSensors Based on Atomic Frequency Metrology
1 mm
Chip-scale atomic clock
Chip-scale atomic magnetometer
Ultraminiature gyroscopegy p
Future atom-based sensors
NIST Chip-Scale Atomic Devices
Pea
Chip-scale atomic clocks:• f/f 10-11 or better
Chip-scale atomic clock Ultraminiature spectrometer
Related devices:• Ultraminiature spectrometer• f/f 10 11 or better.
• <100 mW power consumption.• Potential for low-cost mass production.
• Ultraminiature spectrometerfor telecommunications, chemical identification, atmospheric research, etc.
NIST chip-scale atomic device program since August 2004:
• Several NIST patents
Chip-scale atomic magnetometers:• 10-15 sensitivity: SQUID performance
with no cryogens.Several NIST patents.
• More than 100 NIST publications on chip-scale atomic devices.
• Dozens of conference and workshop presentations.
Ultraminiature NMR gyroscopes:• Navigation grade (0.002 degree).
Commercialization of Chip-Scale Atomic Devices
Symmetricom Chip-Scale Atomic ClockFi t i l hi l t i d iFirst commercial chip-scale atomic device
Introduced January 2011Other commercial products in development by p p y
several companies…
Aims to exceed Cesium beam clock performance for 1000× lower power10-9
CSAC
Research on Ultraminiature Cold Atom Clocks
DARPA IMPACT GoalsPower < 50 mW
Aims to exceed Cesium beam clock performance for 1000× lower power and size.
10-11
10-10 Block IIR RAFS IMPACT 5071A Beam Clock
zCSAC
Size 5 cc (total)
Timing 5 ns 10-12
y()
5071AUncertainty @ 1 day
10-14
10-135071A
IMPACT
Block IIR RAFS
100 101 102 103 104 105 106
t (s)
Sandia/JPL: Trapped 171Yb ionsOEWaves/Aerospace: Kerr optical frequency combsHoneywell:
Laser cooled Rb micro a e interrogationLaser-cooled Rb, microwave interrogationSymmetricom:NIST: Laser-cooled Rb, CPT interrogation
Research on Cold Atom GPS Clock
Source State Dielectric Loaded Ramsey Cavity
DetectionSelection Ramsey Cavity
Approximately same size as current GPS RAFS
Improvements in Time and Frequency DistributionI O ti lI O ti l
Fiber DistributionSystems
Fiber DistributionSystems
Ion OpticalClocks
Ion OpticalClocks
• High accuracy.Di t f f
Frequency CombsFrequency Combs
Future optical clocksf/f ~ 1x10-18
• Direct reference of optical applications to optical standards.
• New applications.
Optical Satellite Optical Satellite
• Directly compare optical frequencies spanning
pp
pDistributionpDistribution
gmore than an octave.
• Link optical to microwave frequencies.
Crucial topic… For another talk….
NIST Fiber Optic Time and Frequency Transfer
tf.nist.gov
Public, searchable database of Time & Frequency Division publications. >2 500 PDFs postedtf i t >2,500 PDFs posted.tf.nist.gov
Time and FrequencyResearch and
Time and FrequencyResearch and JILAJILAResearch and
Metrology in BoulderResearch and
Metrology in BoulderJILAJILA
NIST NIST BoulderBoulder