spacetime: probing for 21st century physics with clocks ...spacetime: probing for 21st century...
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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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
• 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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
• 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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
• 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
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• 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 ?
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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 ….
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
Webb, et al. PRL, 87, 0191301 (2001)
ceh
2
=α
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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.
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
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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
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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
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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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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.
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
– 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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
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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)
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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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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).
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
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
PQE 2005, Snowbird, UtahQuantum Science and Technology Group
Tri-Clock PortabilityRequirements
Mass: 20 kgPower: 30 W