PARCSPrimary Atomic Reference Clock in Space

PARCS Team

• Jet Propulsion Laboratory– Bill Klipstein– Eric Burt– John Dick– Dave Seidel – JPL engineers (lots)– Lute Maleki– Rob Thompson– Sien Wu– Larry Young

• Harvard-Smithsonian– Ed Mattison– Bob Vessot

• Politecnico di Torino– Andrea DeMarchi

• NIST– Steve Jefferts– Tom Heavner– Liz Donnelly– Don Sullivan– Leo Hollberg– Tom Parker– Bill Phillips– Hugh Robinson– Steve Rolston– Fred Walls

• University of Colorado– Neil Ashby

Local Position Invariance

Frequency Shift

“H”

“Cs”

A

Clock Comparisons:MISSION GOALS

•Relativistic Frequency Shift x35

• Gravitational Frequency Shift x12

• Local Position Invariance Test x120

• Realization of the Second 1 x 10-16

• Studies of the Global Positioning System

• With a Cavity Oscillator:- Local Position Invariance- Kennedy-Thorndike Experiment- Michelson-Morley Experiment

GPS

Frequency Shift Measurement

Accumulated Phase Observable:

����

�

�

����

�

������

��

� 221

2

1c

dtABBBt

tA

G

A

ABr

�

�

�

��

� � 2

1

2

1

22

2

22v t

tBBA

Dt

tA

D

ccdt A vr ��

���

�

���

� �

�

�

�

�

� � GravNonBB

t

tA

D dtc �

�� � ar2

1

22 �

�

Limitation: Ground Clock uncertainty of 5 x 10-16.Expected Results: 1.7 ppm

Requirements: position uncertainty of 1 mvelocity uncertainty of 10 m/snon-gravitational acceleration of 130 x 10-9 g

PARCS Configuration

PIU

THERMAL MANIFOLD

CPU

H-MASERELECTRONICS

FRGF H-MASER PARCSADAPTOR

PLATE

FRAM

GPS ANTENNA&

ELECTRONICS

CPP DETECTION

ELECTRONICS

LOSELECTRONICS

LOB

CPP

MICROWAVESYNTHESIZER

DC/DCCOVERTER

STRUCTURE

BULKHEADTHERMAL ZONES

PARCS as a Truss Attached Payload

PARCS as a JEM-EF Payload

SAO Maser

Cesium-Clock Concept

Cesium Clock Physics Package

Design Goals include:• High reliability (1 year operation at 3 Hz)• Fast (< 3 ms time from 100% closed to 90% open)• Non-magnetic (< 1-2 µG stray field at 1cm)• Ultra-high vacuum compatible (<10–12 atm)• Relatively large aperture (> 1 cm)• Cannot disturb microgravity environment.• Light tight

Atom-Beam Shutter

Shutters are used inside the vacuum system to shield the atoms in the clock region from laser light.

Prototype of high-performance non-magnetic shutter. Device is built using commercial PZT actuators and non-magnetic materials

Laser and Optics System

Frequency vs. Phase Modulation

Advantages:Insensitive to Acceleration, Reduced Dead Time, andSystem Is Always On Resonance f0(Cs)

Independent phase control of cavities

Shorter attack times (clearing time is for second cavity only)

f0

1� 2�

const1 ��212�

����

Vibration Sensitivity

Frequency Modulation:

Phase Modulation:

Accelerations at harmonics of the modulation frequency alias in to DC

1-11 m10)()(

�

�� fx

fyFM

1-16 m10)()(

�

�

fxfyPM

�

Dramatic reduction in sensitivity to vibrations

Systematic Frequency Shifts

Major Systematic Effects for PARCS are:

• Zeeman Effect– For 1% field stability, ∆f/f < 10-17

• Cavity Phase Effects– For a titanium cavity and ∆T < 0.1 K, ∆f/f < 5x10-17

• Spin Exchange Shift– For a Ramsey Time of 2.5 s, ∆f/f < 4 x 10-17

• Blackbody Shift– For a ∆T and temperature uncertainty < 0.1 K, ∆f/f ~ 3 x 10-17

Spin-Exchange Shiftwith Phase Modulation

Time-Transfer & Clock Stability

Time Transfer vs. Clock Stability

Averaging Time - seconds1e+3 1e+4 1e+5 1e+6 1e+7

Alla

n Va

rienc

e

1e-17

1e-16

1e-15

1e-14

1e-13

Time-Transfer - 100 ps long term stability

Clock - 5x10-14/�1/2 Time-Transfer - 50 pseconds

PARCS Accuracy Limit

The Next Generation Atomic Clocks -------- Optical ?

Calcium StandardChris OatesAnne Curtis

Mercury StandardJim BergquistSebastian BizeBob DrullingerWayne ItanoRob Rafac

Brent YoungDave Wineland

Frequency ChainScott Diddams Tanya Ramond

Albrecht Bartels(Aachen)Thomas Udem (MPQ)Eugene Ivanov (UWA)

Isabell Thomann

Special Thanks to:• Fred Walls, Tom Parker (NIST)• John Hall, Jun Ye, Steve Cundiff (JILA)•Robert Windeler (Lucent Technologies)

Cold atom Optical Clocks

The fractional frequency instability: (Allan deviation)

Tcycle = time to measure both sides of atomic resonanceQ = line quality factor C = fringe contrast � = averaging timeNatom= # of atoms detected in Tcycle

0

1 1( ) 2

cycley

atoms

TNoise vQ Signal v CN

�

� �

�

�� �

0vQv

��

Eg. What should be possible w/ CalciumOther optical

transitions?� = 657 nm, 456 THz clock transition w/ 1Hz wide line�� = 400 Hz C = 30 %�0 = 456 x 1015 Hz NA=107

�y = 3x10-16 in 1 ms ! Tcycle = 2 TRamsey

�y(�) = 3x10-17�

-1/2�y(�) = 1x10-19

�-1/2 ?

10-17

10-16

10-15

10-14

10-13

Alla

n D

evia

tion

-- In

stab

ility

10-2 100 102 104 106

Averaging Time (s)

H-maser

Cs

Hg+

Ca

1 day 1 monthCa

�

��

1~)(

yInstabilit Limited Quantum

Nff

o

�

Oscillator Stability�

(�)

657 nm probe laser system

657 nm ECDLMaster

Fs-lasersystem

AOM

AOM

Cavity�� = 9 kHz

EOM

Detector

Servo

Slave #1

Slave #2

AOM

Quenched narrow line laser cooling

1S0 (4s2)

3P1

1P1 (4s4p)

423 nm

1S0 (4s5s)552 nm

quenching1.03 �m

657 nm velocity selection

- Use 657 nm pulses to pump atoms towards zero velocity

- Use 552 nm quenching light to pump atoms to ground state

-100 -80 -60 -40 -20 0 20 40 60 80 100Velocity (cm/s)

0.00.10.20.30.40.50.60.70.80.91.0

Exci

tatio

n Pr

obab

ility

hk hk

- First demonstrated with trapped ions (Diedrich et al.)

1-D Quenched narrow-line cooling - Results

-120 -100 -80 -60 -40 -20 -0 20 40 60 80 100 120Velocity (cm/s)

Nor

mal

ized

Flu

ores

cenc

e (a

rb. u

nits

)

vrms = 3 cm/s

T = 4 �K

1.0

0.5

-200 -100 0 100 200Sweep Width (kHz)

0.15

0.20

0.25

0.30

0.35

0.40

Fluo

resc

ence

(V)

0.4525 ms blue cooling/trapping5 ms red/green cooling/trapping

3rd stage single frequency cooling2 x 5 cycles 15 us pulses2 x 8 cycles 25 us pulses (no final green repump)

HWHM = 15.7 kHz(Lorentzian fit of narrow feature)

vrms = 1.0 cm/s (~2/3 of a recoil)

T = 520 nK

60 % of the atomsin narrow peak

3rd Stage, Single Frequency Cooling

Borde-Ramsey Fringes after 4ms Red/Green Trap

Sweep Width (kHz)

Perc

ent A

tom

s Exc

ited

-550 -350 -150 0 150 350 5500

10

20

30

40

11.55 kHz Resolutionsingle 100 s sweep

Optical Bordé-Ramsey fringes - natural linewidth

0 1000 2000 3000 4000Relative Probe Frequency (Hz)

-0.2

-0.1

0.0

0.1

0.2

Dem

odul

ated

Frin

ge A

mpl

itude

(V)

60 seconds data acquisition

Single Hg+ Ion Optical Standard

Tprobe = 20 ms

Tprobe = 120 ms

~ 6.5 Hz

2S1/2

2D5/2

2P1/2

Observefluorescence(� = 194 nm)

“clock” transition @fo � 1.06x1015 Hz

199Hg+

F = 1F = 0

F=2F=3

“Clock”Transition(�=282 nm)

F=0F=1

Hg+ Optical Frequency Standard

J.Bergquist

S. BizeU. Tanaka

B. Young

R. Rafac

W. Itano

R. Drullinger

D. Wineland

Stability about 5x10-15/�1/2

Projected uncertainty 10-18 ?

Optical FrequencyStandard #1

(Mercury)

Optical FrequencyStandard #2

(Calcium)

Comparison of High Stability Optical Frequency Standards:

Using fs optical frequency comb

OpticalFiber

High Stability Reception

Optical Frequency Comb (~1 million “colors”)

180 m

101.645962101.645960101.645958101.645956101.645954101.645952101.645950

x106

100806040200

'10-26-009Hgbeat1' (forward)mean: 101645955.3

2

4

6810-15

2

4

6

Allan Dev

iatio

n

102 3 4 5 6 7 8 9

1002 3 4

Averaging Time (s)

Hg - Ca optical beat '10-26-009Hgbeat1.Allan' '10-26-010Hgbeat1.Allan' '10-26-014Hgbeat1.Allan'

101.645935

101.645930

101.645925

101.645920

x106

806040200

'10-26-014Hgbeat1' (backward)mean: 101645927.1 Hz (Hg AOM shifted by 27 Hz: Corrected ...954.1)

101.645960

101.645958

101.645956

101.645954

101.645952

101.645950

x106

706050403020100

'10-26-010Hgbeat1' (backward)mean: 101645954.7

0.5

0.4

0.3

0.2

0.1

0.0

-0.1

Offs

et o

f rep

etiti

on ra

te fr

om 9

449.

51 H

z (H

z)

60x10340200Time (s)

-4

-2

0

2

Offs

et o

f f0

from

100

MH

z (m

Hz)

60x10340200Time (s)

0.12

0.10

0.08

0.06

0.04

0.02

0.00Offs

et o

f f b

eat f

rom

600

MH

z (H

z)

60x10340200Time (s)

Albrecht Bartels, Tanya Ramond, Scott Diddams

Self referenced (2f-3f) fs comb without microstructure fiber Locked to diode laser locked to Ca reference cavity

14 Hrs continuously locked !Ca Optical cavity converted to 1 GHz vs Maser

Phase-locked f(beat at 456 THz)

f(offset)

Jul 94 Dec 95 Apr 97 Sep 98 Jan 00 Jun 01

Date

-300

-200

-100

0

100

200

300

Mea

sure

d Fr

eque

ncy

-NIS

T V

alue

(Hz)

NIST fs-laser

PTB fs-laserPTB harmonic chain

CCDM

Ca absolute frequency measurements- comparisons

-30

-20

-10

0

10

20

30

f Hg-1

064

721

609

899

142

.6 (H

z)

5260052400522005200051800 MJD

Weighted Average of al l Data: ... 899 143.6(1.0)

Orig inal Measurement [PRL 86 , 4996 (2001)] .. .899 142.6(2.5) Hz

Linear F it: -0.5 ± 1.2 Hz/year

Hg+ Optical Frequency Hg+ Optical Frequency MeasurementMeasurement

Preliminary Preliminary

Bergquist, Bize, Diddams …

I(f)

f

fo

Clock Outputfr ��fA/mCounter

fm

Femtosecond Laser +Microstructure Fiber

frfb

Optical Frequency Standard (fA )

All - Optical Clock

Self-Referencing of Comb Offset

-200

-100

0

100

200

Differ

ence

Bea

t (�

Hz)

6005004003002001000Time (s)

Difference in 1 GHz output between 2 Optical Clocks(1 s Gate Time)

10-16

2

46

10-15

2

46

10-14

2

4

Allan Dev

iatio

n

12 3 4 5 6 7

102 3 4 5 6 7

1002

Averaging Time (s)

Instability of 1 GHz Output of Optical Clock

2 x 10-14 / �� in seconds

Ca Cavity vs. Hg+

2x10-15

3

4

Allan Dev

iatio

n

12 3 4 5 6 7 8 9

102 3 4 5

Averaging Time (s)

118,298,685

118,298,680

118,298,675

118,298,670

118,298,665

118,298,660

118,298,655

118,298,650

Effective Ca - H

g Be

at (H

z)

140x10312010080604020Time (1s per point)

840

-4-8

Res

idua

ls

4

68

10-15

2

4

68

10-14

2

4

68

Alla

n De

viatio

n

12 3 4 5 6

102 3 4 5 6

1002

Averaging Time (s)

Comparison of Hg+ and Ca

Cs clock

FiberNoise