Precision measurement with ultracold atoms and molecules Jun Ye JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado at.
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Precision measurement with ultracold atoms and molecules Jun Ye JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado at Boulder http://jilawww.colorado.edu/YeLabs NASA Fundamental Physics Research in Space Airlie, May 23, 2006 $ Funding $ NIST, NASA, ONR, NSF, AFOSR, DOE Exciting time for light control Continuous wave laser: < 1 Hz stability and accuracy Ultrafast pulse: < 1 fs generation and control Figure of merit: 10-15 Phase coherence after 1015 optical cycles Learn from Giants Hawaii,2001 ICOLS 2005 Hall and Hänsch: Nobel Prize 2005 Frequency comb: state-of-the-art Freq. comb Reduction Gear • Optical Synthesizer 106 :1 Visible n n= n f r – f o I(n) fr n f0 1011 1012 1013 1014 1015 Frequency (Hz) • fr uniformity < 10-18 • Waveform control fo +Df fo 1010 • Absolute inaccuracy < 10-15 • Short term instabilities ~ 10-15 @ 1s • Comb linewidth ~ 0.3 Hz • Df < 10-2 rad, timing jitter < 1 fs 1/ fr = t Ye & Cundiff, Eds., “Comb” book, Springer (2005). Udem, Holzworth, & Hänsch, Nature 416, 233 (2002). Comparison of Hz-linewidth lasers across the visible spectrum Linear Scale 3.0 4/11/ 2006 Optical linewidth: Beat width: 35Hz Hz 2.0 252 mHz 1.0 Ludlow et al., PRL 96, 033003(2006). 20 Hz Laser 2 Cavity 2 1064 nm 0.0 55 60 Laser 2 65 70 75 Hz Laser 1 n Femto comb Laser 1 Cavity 1 700 nm New era for optical atomic clocks Diddams et al., Science 293, 825 (2001). Ye et al, Phys. Rev. Lett. 87, 270801 (2001). Oscillator Dn Feedback (accuracy) na Atoms Ultrastable laser Counter optical frequency synthesizer & counter optical comb RF or optical readout Cool Alkaline Earth – Strontium Xu et al., Phys. Rev. Lett. 90, 193002 (2003). Loftus et al., Phys. Rev. Lett. 93, 073003 (2004). Ido et al., Phys. Rev. Lett. 94, 153001 (2005). Santra et al., Phys. Rev. Lett. 94, 173002 (2005). Ludlow et al., Phys. Rev. Lett. 96, 033003 (2006). Zelevinsky et al., Phys. Rev. Lett. 96, 203201 (2006). 88Sr 1S -3P 0 1 87Sr 1S -3P 0 0 Γ/2π δn/n at 1s 7.6 kHz 7x10-16 T ~ 0.5 photon recoil ~ 220 nK 3P 2 3P 1 < 10mHz ~10-18 3P 0 689 nm 698 nm 1S 0 w0 w0 Spectroscopy at the magic wavelength 1-D Lamb-Dicke Regime η = kx0 = (wrecoil / wz )0.5 ~ 0.23 3P 0 3500 1S 0 wrecoil wtrap clock wtrap Photon counts wtrap 3000 2500 2000 Red sideband 1500 wtrap 1000 Blue SB Carrier 500 -60 -40 -20 0 20 40 Optical frequency (Hz) 60 AC Stark shift of the lattice potential at magic 3P 0 Optical probe nsr - 429228004229900 [Hz] 1S 0 10 0 Lattice Stark shift @ magic: 0(3) Hz/I0 -10 -20 -30 0.6 0.8 1.0 Lattice Intensity [I/I0] 1.2 Absolute Frequency of 2800 1.05 Q ~ 1 x 1014 87Sr 1S 0 – 3P0 Ludlow et al., Phys. Rev. Lett. 96, 033003 (2006). 3200 1.00 3000 2400 Accuracy soon reaching 1 x 10-15 0.95 2600 2000 2400 0.90 2200 FWHM 15 Hz FWHM: 4.6 Hz 2000 Linewidth: 1600 0.85 1800 1600 1400 0.80 1200 200 (30) Hz April, 2006 1200 nsr - 429228004229900 [Hz] Photon counts PhotonCounts counts Photon 2800 -20 March -10 0 2006 10 20 30 2, 0.75-0.9 -0.6 -0.3 0.0 0.3 0.6 Clock Laser Detuning (Hz) -300 -200 -100 0 (kHz) 100 698 nm probe frequency Frequency scan (Hz) Projected stability < 1 x 10-15 at 1 s 60 JILA 2005 40 20 -17.6 ± 2.8 (stat) ± 20 (sys) Hz 0 -20 -40 -60 -80 2006 2005 -100 5/3 5/31 6/28 2/10 3/10 Date (2005 - 2006) Ultracold molecules via Photoassociation 3P 1 (5s2) 1S0 * Narrow linewidth resolves the last few bound states → Determination of long-range potentials and atomic properties * Dipole – dipole interaction similar to Van der Waals * Optically control cold collisions with low atom loss (5s5p) Observed Molecular Lines Dips correspond to trap loss when the PA laser is resonant to make excited Sr2 molecules Zelevinsky et al., Phys. Rev. Lett. 96, 203201 (2006). Cold molecules to test time-variation of electron/proton mass ratio Electronic ~ a Probe Pump npump nprobe Sr2 Vibration ~ me/mp n d(npump – nprobe) < 0.5 Hz Cold OH molecules to constrain a F’= 2 Hyperfine 4 interactions ~ a F’= 1 2P 3/2 OH megamasers Lambda doubling ~ a 0.4 High redshift z > 1 F= 2 F= 1 Darling, Phys. Rev. Lett 91, 011301 (2003). Chengalur et al., Phys. Rev. Lett. 91, 241302 (2003). Kanekar et al., Phys. Rev. Lett. 93, 051302 (2004). Multiple transitions from the same gas cloud (different dependences on a) (Self check on systematics) Current uncertainly in laboratory based experiments is 100 Hz, leading to Da/a ~ 10-5 ter Meulen & Dymanus, Astrophys. J. 172, L21(1972). Stark deceleration Second step: slow the molecules in to the rest frame of the lab + v p + - v p + Phase space selection - Phase space area linked to the deceleration angle (f0) - Phase space rotation (constant density) Resembles a pendulum driven by a constant torque Energy Fnet Conservative process, no cooling Position Cold molecule based precision spectroscopy • Rabi or Ramsey interrogation on slowed OH beam • High resolution and precision • Systematic checks on beam (velocity) effects PMT Decelerator Hexapole Detection can Excitation laser Microwave Interrogation cavity Transition lineshape and center F = 2' F = 2 Transition F' = 2 Population 1.0 Rabi lineshape 0.9 Highest resolution spectral feature (OH) 0.8 0.7 200 m/s beam 1 kHz 0.6 0.5 0.4 Transition frequency determined < 5 Hz (20 x improvement) fcenter = -37.9 ± 11.3 Hz -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 f - 1667359030 [Hz] Long term averaging Hudson et al., Phys. Rev. Lett. 96, 143004 (2006). Weighted standard mean error range Da/a measurement status Da / a = 1 ppm (and better) is now possible to measure over ~10 Gyr. Linear drift model → 10-16/yr. e- e- e- e- 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. Special thanks http://jilawww.colorado.edu/YeLabs Cold Molecules Ultracold Sr E. Hudson B. Sawyer Dr. B. Lev M. Boyd A. Ludlow S. Blatt Dr. T. Zelevinsky Dr. T. Ido Dr. T. Zanon Femtosecond comb & cold atoms S. Foreman M. Thorpe M. Stowe D. Hudson Dr. R. J. Jones Dr. K. Moll Dr. A. Peer Collaborators M. Notcutt, J. L. Hall, J. Bohn, S. Cundiff, C. Greene (JILA) P. Julienne, S. Diddams, J. Bergquist, L. Hollberg, T. Parker (NIST) C. Taatjes (Sandia), E. Arimondo (Pisa)