spacetime: probing for 21st century physics with clocks ...spacetime: probing for 21st century...

PQE 2005, Snowbird, UtahQuantum Science and Technology Group

SpaceTime: Probing for 21st CenturyPhysics with Clocks Near the Sun

Lute Maleki

Quantum Sciences and Technology GroupJet Propulsion Laboratory

California Institute of TechnologyPasadena, CA, USA


Fundamental Physics and Space

Space investigations and fundamental physics play complementary roles:– As a challenging endeavor, extremely sensitive instrumentation isrequired for space with features of high performance, low power, lowmass, and low cost.– As a benign environment (micro gravity, low vibration, high isolation,space and time spans, etc.) space offers the opportunity to performexacting tests of physics.

Fund.Phys. Space

Space environment fortests of fundamental

physics

Space based measurementsenhanced by advance technology


• In the past decade observations from space hasopened new vistas to the universe, and also hascreated new puzzles:– The horizon problem– The accelerating universe– The fine tuning problem– The fate of the universe– Planck-scale physics

• New theoretical models are being developed– String theories, M-theory, quantum gravity– Modified gravity theories– Non-commutative quantum mechanics– VSL Theories

• These are all hints point that point to theemergence of new physics!

Cosmology: Pathway to Fundamental Physics inSpace


• Constancy of “constants”• Robustness of fundamental symmetries• The truism “all theories in physics will

breakdown at some limit…” is no longer analien notion in mainstream physics!

This climate requires experimental tests offundamental physics more urgently than ever!

This is a golden opportunity for fundamentalphysics in space!

Sacred ideas in Physics are open to question


• Climate at NASA and other space agencies

• Priorities (lack thereof) for space research

• General view of the value in “tests oftheoretical models”

• “Unrealistic” view of “priorities” amongst us,the scientists

• All of the above translating into highcost/benefit ratio

But…Challenges remain


• Hope that space agencies come to theirsenses!

• Hope that time will improve funding ofscience

• Seek and identify sensible, lowcost/benefit experiments with multiplefunctions to be used in already plannedmissions

How to deal with reality ?


JPL’s Quantum Sciences and Technology Projects

1. CLOCKS: - experiments in atomic physics are routinely sensitive to sub-mHz energy shifts - expressed in GeV, this is a larger sensitivity than 4 x 10-27 GeV. - testing variation of fundamental constants and the validity of string theory- testing Einstein relativity theories

2. ATOM INTERFEROMETERS- testing the equivalence principle- gravity mapping in space- inertial navigation and drag-free control- atom chips

3. BEC- exploring quantum gas/fluid in absence of gravity- studying matter wave coherence and decoherence- accessing Planck scale physics and the structure of space-time- atom interferometer enhancement

4. EIT5. Others ….


Webb, et al. PRL, 87, 0191301 (2001)

ceh

2

=α


There are also clock comparison tests

Clock Tests: Ultrahigh resolution determined by clock accuracy over a few year baseline - can be repeated, and improved

Astronomy Tests: Low resolution determined by spectroscopy of distant gas clouds over 1010 yr period.


Hyperfine Transitions

Alkali atoms and alkali-like ions scale as hydrogenbut with relativistic corrections Frel(αZ):

cRmm

ZFdnd

nz

ZgAp

erel

nIs ∞−−

Δ−= )1)(1)(()1(

*38

3

22 εδαα

Prestage, Tjoelker, MalekiPRL, 74, 3511(1995)

Hydrogen hyperfine splitting scales as:

cRmm

gAp

eps ∞= 2

38α =+ )

21

(IAs Clock frequency

Finite Size nuclear charge4% Cs,…, 12% Hg

Finite Size nuclear Magnetic Moment0.5% Cs,…., 3% Hg

Z

0 10 20 30 40 50 60 70 80 90

Fre

l (

α

Z)

1.00

1.15

1.30

1.45

1.60

1.75

1.90

2.05

2.20

2.35

2.50

Relativistic corrections to wavefunctionat the nucleus


Hyperfine Transitions

The frequency of transition:

f = α 4 mMmc2

hF(αZ )

H Rb Cs Hg+

H 0 0.3 0.74 2.2

Rb -0.3 0 0.45 1.9

Cs -0.74 -0.45 0 1.4

Hg+ -2.2 -1.9 -1.4 0.

α Dependence of Hyprefine Transitions

.

α s

ensi

tivity

com

paris

on

Hg+

Yb+

Cd+

Cs

Rb

H-maser


Summary of Clock Comparison Tests

Bize,.. Drullinger,Heavner,…..Bergquist

PRL 90, 150802-1(2003)

<7x10-15/yrOptical Hg+ vs Cs

Optical/hfs

Marion,..,Bize,..Santarelli, Clarion

PRL 90, 150801-1(2003)

<7x10-16/yrRb vs Cs

(hfs)

Prestage, Tjoelker,Maleki

PRL 74, 3511 (1995)<8x10-14/yrHg+ vs H-Maser

(hfs)

Stein, Turneaure

27th FrequencyControl Symposium,p414 (1973)

<10-11/yrSCSO vs Cs hfs

0.6α

p

eCs m

mg

44.0−αµ

µ

Cs

Rb

2.2αµ

µ

H

Hg

74.3αp

eCs m

mg


Observed variations

α≈10 −5

Observation of an α variation appears to be at odds with Earthmeasurements:

(null result of Oklo < 10-6, or 10-17/yr, JPL (1995) < 10-14/yr,Paris (2003) < 10-16/yr, NIST (2003) < 10-16/yr)

Webb, et al. PRL, 87, 0191301 (2001)

variations in α is observed at 0.5 < Z < 3.5Δα

But α can be changing with position in space!

α = α0(1 + εU/c2).

(Sandvik, Barrow, and Magueijo) 24105rc

GMx −≈

Δ

αα


Clock Tests for Spatial Variations of α

• Spatial variations of α = α(UEarth + Usolar + …+ Ucosmos)

• Search for clock differential rate along a trajectory near sun whereUsolar ≈ 10-6

• Sensitivity to α time variations enhanced to 10-20/year from a clockcomparison to 10-16 in the solar potential.

• 4 orders of magnitude improvement over observationalastronomy

106

16

212

1 1010

101))()((ln −

−

−

≈≈≈−=potentialsolarofchange

ratesclockofchange

dU

dZFLZFL

A

A

dU

dreldreld

clock

clock αα

yeardU

dH

dU

d

dt

dU

dU

d

dt

d/10

1111 100

−===α

αα

αα

αα

α


α-varying cosmologies have been devised to ‘explain’ the cosmologicalchanges (Sandvik, Barrow, Magueijo, PRL 88, 21 Jan. 2002)

))(()]()([)( trUZLZLty BAAB −= ε

Signature for a-variation during solarflyby

Time from Perihelion (hours)

0

5

10

-72 -60 -48 -36 -24 -12 0 12 24 36 48 60 72

Clo

ck D

iffe

renc

e F

requ

enci

es

(Hz

at 4

0 G

Hz)

Hg,CdHg,YbYb,Cdε ∼ 10-10 can be detected in a

clock comparison with 10-16

stable clocks with single flyby


Science TeamJPL

John Armstrong

Lute Maleki (PI)

John Prestage

Eric Adelberger – University of washington

Thibault Damour - Institut des Hautes Etudes Scientifiques

Kenneth Johnston – US Naval Observatory

Alan Kostelecky - Indiana Universit

Claus Lemmerzhal – Heinrich-Heine-Universitaet Duesseldorf

Kenneth Nordtvedt - Montana State University

US/International

Space-Time Team

Proposal Manager - Jim Randolph

System Engineer - George Sprague

Attitude Control - Ed Mettler

Trajectory/Mission - Gene Bonfiglio

Thermal Control - Bob Miyake

Telecommunications - Bill Moore

GDS/MOS Development (JPL) - Randy Reed

GDS/MOS Development (Univ. of CO) - Elaine Hansen

Industrial Partner:

LMSSC - Sunnyvale


LAUNCH

(C ~ 120 km 2/ sec 2 )

JUPITER GRAVITY ASSIST FLYBY

50 d

PERIHELION (4Rs)

EARTH at PERIHELION( at Quadrature)

Mission Lifetime = 3 yr 8 mon8.68 Rj

X band to DSN

≤100 bps

S/C Mass Budget: 200 kgClock Payload Requirements

Mass: 20 kgPower: 30 W

v/c ~ 10-3 at PerihelionAfter 2 years free fall


Tri-clock Approach

Instrument:A tri- clock based on trapped ions, Hg+ ,Yb+, and Cd+, in the same environment,based on JPL’s LITS design

–Mass: 20 Kg for tri-clock–Power: 30 W for tri-clock–Data Rate: < 100 bps

• Three ion traps in same environment:

– Common vacuum system, thermal environment, magnetic environment

• Allows elimination or minimization of environmental perturbations

– Common LO

• Allows use of high performance quartz, and still achieve 10-16

stability

• Most electronic components and circuits are common

• Mass and power requirements compatible with limitations

• Provides needed stability (10-16) at 40,000 s

• Comparison made onboard, only results are beamed back

Clocks will be based on LITSdeveloped at JPL for NASA’sDeep Space Network.

-- Operates with lamp and buffergas cooling.

-- Currently three units operating inthe DSN. A flight unit, as aprototype for GPS, is underdevelopment.

Compact 1-liter sized

Work done by J. Prestage et al.


– Comparable size/mass to s/c USO

– Stability 100x improvement over USO at 1hour averaging

– With USO as LO, will supply

stability at 10-16 level onboard s/c.– Enables simultaneous navigation

of multiple s/c in planetary orbit

with a single DSN antenna.

– Cost savings in antenna use,

4M$ per s/c per year.

Small ion clock for deep space navigation


Sang Chung, John Prestage

• Demonstrated 1-2 x10-13 stability at 1 second, averaging to 10-

15 (H-maser quality)– First small clock operation with ion shuttling, multi-pole and 2 layer magnetic

shield and closed vacuum system.

10-13

Averaging Time (Tau)1 10 100 1000 10000 100000

Sigm

a

10-14

10-15

10-16

Microwave Feed

Inner shield

Sapphire Windows


Full Trap Design Completed; Fabrication Started

• Ion traps are brazed, “onepiece” with metallized electricalinterconnects; no screws, etc.used as fasteners.

• 16-pole provides betterisolation to stray external fields,for 0.056” moly rod size.

• Non-magnetic parts requiredfor high Q atomic resonance(Q~1011).

Multi-pole microwave resonance trap0.056” moly rods

Quadrupole Ion Fluorescence trap0.032” Moly rods

Metallized Trap Electrode connections

(yellow)

Ceramic Trap Electrode Supports (green)


Compact Optical System Design

• UV light detectorswith power supply,amp/discriminatorchip are integratedinto module.

• Isolated from rf powerin lamp driver modulewith rf tightcompartments asshown below

Fluorescence Detection Arms

Photomultiplier Tubes

10-12 grade VCXO


Cadmium rf lamp

Towards development of the lamp based 113Cd+ ion atomic clock

B. M. Jelenkovic, S. Chung, J. D. Prestage and L. MalekiJet Propulsion Laboratory/Caltech, Pasadena, CA 91109

IntroductionThe motivation for the development of new atomic clock is to test for a possible variation of the fine structure constant. Flying two (or three)atomic clocks through the strong gravitational field of the Sun and measuring changes in the ratio between the frequencies of two microwaveclocks, will be a unique test of the variation of the fine structure constant. A time variation of the ratio of transition frequencies, i. e. the hyperfine interaction constant A, for two elements with atomic numbers Z1 and Z2 is

• F(Z) is a strong functions of alpha for high Z nuclei and can be used to detect the temporal or spatial variation of alpha [1].

• We worked towards development of Cd+ ion atomic clock based on technologies used for the discharge rf lamp based 199Hg+ atomic clock.The 199Hg+ atomic clock has required stability of 10-16 in ~10 hours where changes in the clock frequency violating EEP and Standard Modelare expected to be the largest. Similar technologies used for small two (three) clocks helpsin developing space flight technology package.

Results

• The resonant frequency is 15.199862903 GHz for unshielded ambient magneticfield, + 45 Hz compared to value at zero magnetic field [2].• The short term clock stability is ~5 x 10-13 τ−1/2

Experiment

Pumoing scheme for Cd atomic clockEstimated overlap of the trapped 113Cd+ absorption profile

with 106Cd+ emission profile

dt

dZFZF

A

A

dt

d αα1

)]()([ln 212

1 −=

F=1

F=0

F=1

F=0

2S1/2

F=2F=1

2P1/2

2P3/2

113Cd 106Cd

15.2

1.036

0.726

2.45

2.1

F=1/2

a) b)

-4.00E+009 0.00E+000 4.00E+009 8.00E+0090.0

0.2

0.4

0.6

0.8

1.0

113Cd+, F = 0

113Cd+, F = 1

106Cd+

Em

issi

on

, A

bso

rptio

n (

a.u

.)

Frequency (Hz)

-4.00E+009 0.00E+000 4.00E+009 8.00E+0090.0

0.2

0.4

0.6

0.8

1.0

113Cd+, F = 2 106Cd+

Em

issi

on

, a

bso

rptio

n (

a.u

.)

Frequency (Hz)

a) 113Cd+ and 106Cd+ ion energy level diagram and the pumpingscheme

b) Emission from 106Cd+ lamp at 1000 K (solid curve) andabsorption by trapped 113Cd+ at 500 K (dotted curve). Top is for2P1/2 and bottom for 2P3/2

212 214 216 218 220 222 224 226 228 230 2320

40000

80000

120000

160000

200000

Cd I228.6 nm

Cd II2S

1/2 - 2P

1/2

226.6 nmCd II2S

1/2 - 2P

3/2

214.5 nm

Pho

ton

coun

t (se

c-1

)

Wavelength (nm)

140 145 150 155 160 165 170 1750

40000

80000Cd II (214 nm)

Pho

ton

coun

t (se

c-1

)

Temperature (0C)

106Cd rf lamp

Cd rg lamp is a quartz bulb inserted into cooper resonator.The bulb has ~ 1Torr of Ar and piece of 1-2 mg of106Cd

UV spectrum from 106Cd lamp. The insert shows the intensity of Cd II line at 214.5 nm vs the lamp temeperature.

UV photondetector

UV rf discharge106Cd lamp

113Cd oven

15.2 GHz

Two six inch spherical mirrors were used to focus the UV kight from the 106Cd lamp to the trap region and to collect the scattered light from the ions on the detector.

Cadmium oven has a piece of ~ 5 mG of 113Cd and operates at ~65 0C.

The microwave interrogation signal at ~15.2 GHz was obtained by summing a 950 MHz signal with ~7 MHz andfeeding the resulting signal into a step recovery diode. The ~7MHz side band of the 16-th harmonic was swept for frequency scan around the hyperfine resonance.

-50000 -25000 0 25000 500000.0

5.0x103

1.0x104

-5 dBm

Frequency (Hz)

-40000 -20000 0 20000 400000.0

2.0x104

4.0x104

-12 dBm

Ph

oto

n c

ou

nt

(se

c-1

)

Frequency offset (Hz)

-10000 -5000 0 5000 100000.0

2.0x104

4.0x104

-21 dBm

Frequency offset (Hz)

Spectra of the hyperfine transitions at ~15.2 GHZ Rabi microwave resonance

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0

5000

10000b)

0.17 Hz

Pho

ton

coun

t (se

c-1

)

Frequency + 15199862902.5 (Hz)

0.0 0.5 1.0 1.5 2.0

0

25000

50000

a)

0.35 Hz

Pho

ton

coun

t (se

c-1

)

Frequency (Hz)

Rabi microwave resonance for ioninterrogatino time a) 2.5 s and b) 5 s

0 10 20 30 40

22000

24000

26000

Ions dumped

Lamp on

Lamp offMW on

Pho

ton

coun

t (se

c-1

)

Time (sec)

Spectra of the hyperfine transitionsaround 15.2 GHz for various microwave power

lamp

microwave

countS+B B

TI

The sequence of pulses applied to the lamp, microwave generator and counter at each frequancy

Fluorescence sequence showing signal overshut (i.e puping) .aftermicrowave signal was turned off and lamp was turn on

References:1. J. D. Prestage, R. L. Tjoelker and L. Maleki, Phy. Rev. Lett. 74, 3511 (1995).2. U. Tanaka et al., Phys. Rev. A 53, 3982 (1996).


Conclusion Remarks

• Current climate is “not supportive” of the development of new

space missions in fundamental physics

• Many of the tools of investigating fundamental physics in space

have multiple uses

• By carefully choosing the appropriate technology we can enhance

the opportunity for new tests of fundamental physics in space


CollaboratorsClocks:

John Prestage

John Dick

Sang Chung

Thanh Le

Brana Jelkovic*

Dmitri Strekalov

Atom Interferometer:

Nan Yu

James Kohel

James kellogg

Lawrence Lim

BEC/Atom chip:

Rob Thompson

Nathan Lundblad

David Aveline

Micro-Cavities

Andrey Matsko

Anatoliy Savchenkov

Vladimir Ilchenko

Makan Mohageg

Ivan Grudinin


Tri-Clock PortabilityRequirements

Mass: 20 kgPower: 30 W

spacetime: probing for 21st century physics with clocks ...spacetime: probing for 21st century...

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