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Precision Molecular Ion Spectroscopy:
A New Probe for New Physics
Brian Odom
milliKelvin Molecular Ion Research
… a few years ago
Stephan SchillerDusseldorf
Michael DrewsenAarhus
milliKelvin Molecular Ion Research
Stephan SchillerDusseldorf
Michael DrewsenAarhus
Ike ChuangMIT
Eric HudsonUCLA
Brian OdomNorthwestern
Ken BrownGeorgia Tech
… today
Tobias SchaetzMPI-Garching
Stephan WillitschBasel
Piet SchmidtPTB
Zhang Chaobo Nanyang
Kunihiro Okada Tokyo
Yoshiki MoriwakiToyama
Precision AMO Spectroscopy ( for the “m”)
Atomic optical spectroscopy
Best molecular spectroscopy
Atomic microwave spectroscopy
Why are Molecules so Far Behind?
Why cycle?• Laser cooling• Single atom detection
Atoms are easy …molecules are hard
HEP-Inspired Molecular Possibilities
p+
e-
Parity violation at molecular level
Time-variation of constants
Molecular enhancementDeMille, et al, PRL 100, 023003 (2008)
Nuclear spin-dependent (NSD) parity violation
1-sigma constraints on PNC meson couplingsHaxton et al, Phys Rev C 65 045502
Fundamental electric dipole moments
Time-Varying Constants
• Possibilities:• Continuing variation in time • “Phase-shift” behavior• Variation with space, not time• Variation with matter density, not time
• We cannot predict rate or type of variation, but…
(30 40)
Is this even possible?Kaluza-Klein, string theories allow/predict variations.
What are the predictions?
electron-proton mass ratio mfine structure constant a
Units Ain’t Welcome In These Parts
+
-
Experiment: Count the Cs clock ticks for a photon to cross H atom
Conclusion: 1 s defined by Cs, c is defined…so rH is changing
Say that number changes from year to year…
But…if 1 m were defined by rH , c still defined, we conclude that wCs is changing
Talk of unitful constants changing obscures the physics
Cs
What Does This Have to Do with Dark Energy?
?
Strategies for a Hard ProblemStrategy 1: The denominator approach D / m m ≈ 10-6, T ≈ 109 years
Data from Ultraviolet and Visible Echelle Spectrograph mounted on the Very Large Telescope of the European Southern Observatory Ubachs, Buning, Eikemma, and Reinhold, J Molec. Spect. 241, 155 (2007)
T
Strategy 2: The numerator approach T ≈ 1 year… D / m m < 10-15 ???
State of unConstant Affairs
Quasar absorption lines:
176 10 / yr
1764 (14) 10 / yr
Al+/ Hg+ clock comparison: 173.9 10 / yr
Quasar absorption lines:151.7 (0.5) 10 / yr
Ubachs, Buning, Eikemma, and Reinhold,J Molec. Spect. 241, 155 (2007)
150.3 10 / yr
H2:
NH3 / (CO, HCO+, HCN):Henkel et al, Astronomy and Astrophysics 440, 893 (2005)Combes and Wiklind, Astrophys J 486, L79 (1997)
a
mLaboratory: 1565 10 / yr
Chardonnet, http://www.ptb.de/ACFC2007/present.htm SF6 :
Laboratory:
m is way behind … because it needs molecules!
Molecular Degeneracy Can Help
Some systematics, such as clock instability or Doppler shift, impose fractional frequency error
Molecular complexity is definitely a good thing here
Ba+ Laser Cooling
Why Barium?• Heavy (effective sympathetic cooling of heavy molecular ions)• Cooling transition is most red option
Our First Ion Trap
Fluorescence Images of Trapped Ba+
• At low enough temperature (~ 0.1 K) crystallization occurs• Ba-138 is pushed left by light pressure
Trapped Barium Coulomb Crystals
… and Throw in Some Molecular Ions
(Following Drewsen at Aarhus and Schiller at Dusseldorf)
Ba+ fluorescing ions
BaH+ dark ions,
(probably
milliKelvin!)
Loading SiO+
First ablate Ba
target
Then ablate SiO
target
Quantum Logic Spectroscopy,
State ReadoutWorld’s best spectroscopy (QLS) is on a non-laser cooled ion…Why not on a molecular ion?
Internal state
Motional state
n=1n=0
n=1n=0
Spectroscopy ion
Logic ion
?
Spectroscopy ion is hard to read out, but logic ion is easy
Internal state
Motional state
n=1n=0
n=1n=0
Spectroscopy ion
Logic ion
Quantum Logic Spectroscopy,
State TransferWorld’s best spectroscopy (QLS) is on a non-laser cooled ion…Why not on a molecular ion?
Spectroscopy ion is hard to read out, but logic ion is easy
mQLS Trap Design
3 mm
mQLS Table and Trap
mQLS Vacuum Chamber Assembly
The People Doing the WorkPostdocsJoan MarlerJason Nguyen
Grad StudentsChien-Yu LienYen-Wei LinVaishnavi RajagopalChris SeckDavid TaborMing-Feng Tu
UndergradsMarc BourgeoisGreg McGlynnIngrid RinglerLauren RuthScott Williams
… and The People Paying for ItIGERTQuantum Coherent Optical and Matter Systems
Extras…
Sounds Great.What’s the
Catch?
Rotational Cooling of Hydrides
Schiller and Drewsen groups (2010)
What would still be nice?• Faster cooling• Applicable to heavier species
Cool Rotations into Electronic Excitation?
We would like diagonal Franck Condon Factors
Femtosecond Pulse Shaping
1 cm-1 resolution currently achieved
Pulse-Shaping for AlH+ Rotational Cooling
Current resolution is sufficient for cooling
Simulation of AlH+ Rotational Cooling
Expect ~7 ms cooling timescale (compare with 10 s timescale of vibrational excitation technique)
Review: Radiofrequency Ion Traps
http://www.exphy.uni-duesseldorf.de/ResearchInst
~ 5 mm +
+- -
Review: Radiofrequency Ion Traps
http://www.exphy.uni-duesseldorf.de/ResearchInst
~ 5 mm -
-+ +