Precision measurement with ultracold atoms & molecules Jun Ye JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado at Boulder $ Funding $ NIST, ONR, NSF, AFOSR, NASA, DOE http://jilawww.colorado.edu/YeLabs US – Japan Seminar, Breckenridge, August 23, 2006
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• 3P0 g-factor different than 1S0 due to HFI• Shift of ~110 x mF Hz/Gauss for ΔmF=0• State preparation, field control• HF structure introduces slight lattice polarization sensitivity
Differential g-factor – Tensor polarizability
1S0
3P0
HFI
1P1
3P1
I = 9/2
mf
-9/2
+9/2
1S0
3P0
mf
-9/2
+9/2
1S0
3P0
Santra et al., Phys. Rev. Lett. 94, 173002 (2005).Hong et al., Phys. Rev. Lett. 94, 050801 (2005).Barber et al., Phys. Rev. Lett. 96, 083002 (2006).
-400 -200 0 200 4000.00
0.02
0.04
0.06
0.08
0.10
-9/2-7/2
-5/2
-3/2
-1/2+1/2
+3/2
+9/2+7/2
3 P 0 Sig
nal (
Nor
m.)
Laser Detuning (Hz)
+5/2
Optical Measurement of Nuclear g-factor (NMR-like experiment in the optical domain)
π
21+
29+
23+
25+
27+
21+
29+
23+
25+
27+
21−
27−2
9−
25−
23−
21−
27−2
9−
25−
23−
01S
03P
No net electronic angular momentumΔg = -108.5(4) Hz/(G mF)3P0 lifetime 140(40) s
1S0
3P0
0 1 2 3 4 5 60
2
4
6
8
Occ
urre
nces
Transition Linewidth (Hz)
Fourier Limit ~1.8 Hz
-6 -4 -2 0 2 4 6
0.00
0.02
0.04
0.06
0.08
0.10
3 P 0(mF=5
/2) P
opul
atio
n
Laser Detuning (Hz)
1.5 Hz
-6 -4 -2 0 2 4 6
0.00
0.02
0.04
0.06
0.08
0.10
3 P 0(mF=5
/2) P
opul
atio
n
Laser Detuning (Hz)
2.1 Hz
Coherent spectroscopy Q ~ 3 x 1014
-60 -30 0 30 60 90 1200.00
0.04
0.08
0.12
0.16
0.20
3 P 0(mF=5
/2) P
opul
atio
n
Laser Detuning (Hz)
-10 -5 0 5 100.00
0.04
0.08
10 Hz
1.7 Hz
Ramsey
Ultracold Sr2 molecules via narrow-linePhotoassociation
3P1 + 1S0
1S0 + 1S0
Laser detuning
Trap Loss
< 100 kHz
Zelevinsky et al., Phys. Rev. Lett. 96, 203201 (2006).
Narrow-line Photo-association Spectroscopy
• New Territory for PAS
• Interesting regime, C3 C6 crossover
• Ground/Excited state similar for large detunings
• Hyperfine-free for bosonic isotopes• Useful for precision tests• Optical control of cold collisions with
low loss
66
33
RC
RC
≈ at Δ~500 MHz
(5s2) 1S0
689 n
m, γ
= 7.
6 kH
z
3P1 (5s5p)All bound states are resolved by the narrow line
Theory: Paul Julienne
σ-polarizedprobe
magicStarkshift
1S0
3P1
mJ0 +1-1
0.5 Wstanding wave
Ωlattice>>εrecoil
PAlaser
Doppler- and recoil-free
Photoassociation inside a Magic wavelength lattice
3P0
1S0
700 750 800 850 900Laserwavelength nm
-450-400-350-300-250-200
Star
k sh
ift (k
Hz)
1S0
3P0
3P1
Photoassociation: Experiment vs. theory
Nine least bound states measured
10-5 agreement for near detuning, 0.1-1% agreement deeper in the potential curve
Ground State Molecules
Vg
0uSimilar excited and ground state wavefunctions~90% of molecules in 8.4 GHz state decay to single g.s.
Should be possible to drive Molecules to deepest g.s.
Sr2
Magic wavelength trap for molecules?Theory: P. Julienne and A. Derevianko
νpump νprobe
δ(νpump – νprobe) < 0.5 Hz
ν
Time-variation of electron-proton mass ratio?D. DeMille, private communications (2005). Chin and Flambaum, Phys. Rev. Lett. 96, 230801 (2006).
Test of fundamental constants
• Early universe• Not so clear…Webb et al., PRL 87, 091301 (2001).Astron. Astrophys. 415, L7 (2004).– Conflicting results
Impact
α: fine structure constant•Modern epoch
• Atomic clock measurementsare consistent with zero
Δα/α < 10-15/yr
ν
Cold OH molecules to constrain α
Hyperfineinteractions ~ α 4
Lambda doubling ~ α 0.42Π3/2
F’= 2
F’= 1
F= 2
F= 1Multiple transitions from the same gas cloud (different dependences on α)(Self check on systematics)Current uncertainly in laboratory based experiments is 100 Hz,leading to Δα/α ~ 10-5
ter Meulen & Dymanus, Astrophys. J. 172, L21(1972).
OH megamasers
High redshift z > 1Darling, Phys. Rev. Lett 91, 011301 (2003).Chengalur et al., Phys. Rev. Lett. 91, 241302 (2003).Kanekar et al., Phys. Rev. Lett. 93, 051302 (2004).
Stark Decelerator
Slower electrodes
Star
k en
ergy
Position
G. Meijer
OH after the Stark-decelerator
1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.80.00
0.25
0.50
0.75
1.00
OH
den
sity
(arb
.)
Time (ms)
370 m/s
336 m/s
300 m/s
259 m/s211 m/s
148 m/s 33 m/s
Bochinski et al., Phys. Rev. Lett. 91, 243001 (2003); PRA 70, 043410 (2004).
Beam: 550 m/s to restTemp: 1 K to 10 mK104 – 106 molecules105 – 107 /cm3 density
Cold molecule based precision spectroscopy
PMT
Excitation laserMicrowave Interrogation cavity
HexapoleDecelerator
• Rabi or Ramsey interrogation on slowed OH beam• High resolution and precision• Systematic checks on beam (velocity) effects
Detection can
Weightedstandard meanerror range
Hudson et al., Phys. Rev. Lett. 96, 143004 (2006).
Precision measurement of OH structure
Δα/α measurement status
Δα / α = 1 ppm (and better) is now possible to measure over ~10 Gyr.Linear drift model → 10-16/yr.
Astrophysical measurements later this year plan better than 100 Hz accuracy.
Deep surveys of OH megamasers are active from the local Universe to red shift z ~ 4.
Optical clock comparisons ongoing, but test only modern epoch.
Tests on Δ(me/mp) / (me/mp) is possible (W. Ubach, PRL 92, 101302 (2004); PRL 96, 151101 (2006).)
e- e-
e- e-
Special thanks
Femtosecond comb& cold atoms
S. ForemanM. ThorpeD. HudsonM. StoweDr. A. Pe’erDr. R. J. Jones (Arizona)Dr. K. Moll (Precision Ph)
Ultracold Sr & Sr2
M. BoydA. LudlowS. BlattDr. T. ZelevinskyDr. T. ZanonDr. T. Ido (NICT,Tokyo)
Cold Polar Molecules
B. SawyerB. StuhlDr. B. LevE. Hudson (Yale)
http://jilawww.colorado.edu/YeLabs
Collaborators
J. Bohn, S. Cundiff, C. Greene, J. Hall (JILA) P. Julienne, S. Diddams, J. Bergquist, L. Hollberg, T. Parker (NIST)
E. Eyler (UConn), F. Krausz (MPQ)
|e,n>
|g,n+1>
|e,n-1>
|g,n>
Dipole force fluctuations: Heating and position-dependent decoherence
FORT beam
CQED probe
Caltech cavity QED lessonKimble group, 1999
The Solution:Match the AC Stark shift
between |e> and |g>
|e,n>
|g,n+1>
|e,n-1>
|g,n>
Kimble et al. ICOLS 99
Problems in the neutral atom land
Reproducibility
-20 0 20 40 60 80 1001201401600
20
40
60
80
100
120
Sam
ples
Optical frequency deviations (Hz)
40 60 80 100 1200
10
20
30
40
50
60
Sam
ples
Optical frequency deviations (Hz)
0 200 400 600 800 100066
68
70
72
74
76
Opt
ical
line
cent
er fr
eque
ncy
(Hz)
Error tolerance (Hz)
ν0 = 429,228,004,229,800 Hz
Center: 71.4 Hz ± 0.4 Hz
March – June 2006: 1020 measurements3 different NIST Cs-calibrated masers
1020 samples
1000 samples
2 Hz optical
Statistical error < 1 x 10-15
Global Sr Clock Comparison
800
820
840
860
880
900
920
940
960
JILA 2006(Preliminary)
Measurements Freq
uenc
y- 4
29,2
28,0
04,2
29,0
00 H
z
Tokyo 2005
JILA 2005
Paris 2006
Tokyo 2006? PTB?
Takamoto et al., Nature 435, 321 (2005). Ludlow et al., Phys. Rev. Lett. 96, 033003
~10 months
?
1 MHz error in lattice wavelength → 5 x 10-18 clock inaccuracy
How Magic is the wavelength?
813.2 813.4 813.6 813.8
-400
-300
-200
-100
0
100
200
300 R
elat
ive
Clo
ck F
requ
ency
(Hz)
Lattice Wavelength (nm)
Sensitivity 884(15) Hz/nmI0= 10 kW/cm2
Ludlow et al., Phys. Rev. Lett. 96, 033003 Brusch et al., Phys. Rev. Lett. 96, 103003 (2006).