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K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, T. Fukuhara,

Photoassociation Spectroscopy of Ytterbium Atoms with Dipole-allowed and Intercombination Transitions. K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, T. Fukuhara, A. Yamaguchi, S. Uetake, Y. Takasu, and Y. Takahashi, Kyoto University.

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K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, T. Fukuhara,

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  1. Photoassociation Spectroscopy of Ytterbium Atoms with Dipole-allowed and Intercombination Transitions K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, T. Fukuhara, A. Yamaguchi, S. Uetake, Y. Takasu, and Y. Takahashi, Kyoto University Ultracold Group II atoms: Theory and Applications 06/Sep/18 ITAMP についてのCOE報告会

  2. Ytterbium Group II

  3. 2000 Cold Alkaline-Earth Atoms (in ITAMP) 2003 Cold Alkaline-Earth Atoms (in Copenhagen) 2006 Sep/18-20 Ultracold Group II Atoms (in ITAMP) Workshop on ultracold group II atoms Number of invited speakers Experiment Theory 4 Atomic clock 1 Photoassociation 4 5 Novel species/mixtures 5 1 Others 3 5

  4. Next generation atomic clock 1S0-3P0 atomic transition has extremely narrow linewidth ( <0.1 Hz), and is inert to a magnetic field. The atoms trapped in an optical lattice with the magic wavelength are free from the Doppler broadening and the collisional shift. Frequency standard with  /  ~ 10-17 Precise frequency measurements of Sr and Yb in 1D lattice have been presented (NIST, JILA, SYRTE, PTB groups). The precision is about 5Hz.

  5. g R Photoassociation (PA) Ultracold atoms has narrow thermal distribution, so free-bound transitions (photoassociation) are observed with high resolution. This photoassociation is a powerful tool for probing rovibrational levels near the threshold and scattering states. Atomic parameters such as radiative lifetimes and scattering lengths are determined precisely. Such parameters are determined for Sr, Ca, and Yb. Theory for optical control of collision, PA in low dimensions

  6. Novel species/mixtures Magneto-optical trap (MOT) of Ra (radium, =15day) Measurement of nuclear EDM MOT of Li-K-Sr mixture Novel cooper pair (heteronuclear, FFLO, etc.)

  7. Summary of my talk

  8. dipole allowed, 399 nm =5.5ns (Linewidth=29MHz) clock transition intercombination transition 556 nm, =874ns (Linewidth=182kHz) 168 170 172 173 174 176 Mass number 171 Nuclear spin i 0 0 1/2 0 5/2 0 0 0.13 3.05 14.3 21.9 16.2 31.8 Abundance(%) 12.7 (6s6p)1P1 Level Diagram of Yb (6s6p)  =15s 3P2 3P1  ~  3P0 (6s2)1S0

  9. Outline 1. Experimental procedure 2. Determination of scattering length of 174Yb 3. Two-color PAS 4. Intercombination PAS of 4 isotopes 5. Optical Feshbach resonance

  10. anti-Helmholtz coils Zeeman slower 399 nm atomic Zeeman slowing laser (～40 mW) beam 556 nm MOT laser (～30 mW each) Experimental procedure Typical time chart ～10s slower MOT ～6s horiz. FORT vertical FORT ～100ms PA probe

  11. Off resonance 1.0 transmission 556 nm PA laser 0.0 (～0.1W/cm2) 399 nm probe laser 240mm (～0.01W/cm2) On resonance absorption image 532 nm FORT laser CCD camera (7→0.2 W, 0= 12 m) N ~105 (7 W 0= 80 m) n ~1014 cm-3 Experimental procedure Typical time chart ～10s slower MOT ～6s horiz. FORT vertical FORT ～100ms PA probe

  12. Determination of scattering length of 174Yb using dipole-allowed PAS

  13. Spectra of dipole-allowed PAS PAS of 1S0-1P1 transition at ~1 K

  14. Scattering length a of 174Yb is 5.53  0.11 nm C6 potential coefficient is 2300  250 a.u. (with taking account of other sources of error.) Ground-state wavefunction Wavefunction obtained from PA rates to various vibrational states

  15. Two-color PAS

  16. 1 2 Lightshift Last bound state level 10.63 MHz Expected shift (MHz) Two-color PA spectra of 174Yb Recently, we succeeded in observing two-color PAS spectra for 174Yb at ~1 K. 174Yb 1S0-1P1 Raman transition Frequency difference (MHz)

  17. Two-color PA spectra of 174Yb 1 2 Dark state (1 is scanned) Next-to-the-last state level 268.6 MHz These two-color PAS results determine C6 and a more precisely. Autler-Townes spectroscopy (2 is scanned) Frequency difference (MHz)

  18. ~54 Å The scattering length a can be described with the phase . 168 172 173 Mass number 170 171 174 176 Gribakin et al., PRA 48, 546 (1993). Scattering length ? Å ? Å ? Å ? Å ? Å ? Å ~54 Å 168 172 173 Mass number 170 171 174 176 Scattering length of other isotopes small neg. ? +10 - 5 Scattering length ? pos. small large 6 nm small? Two-color PA spectroscopy of some isotopes will reveal the scattering lengths of all the isotopes and their combinations.

  19. Intercombination PAS of bosonic (i=0) isotopes (174Yb, 176Yb )

  20. v’ = 9 v’ = 8 v’ = 10 PA spectrum of 174Yb At a low temperature of ~4 K, only transition from s-wave scattering state was observed. v’ = 7 Even the vibrational level at 3 MHz from the disso- ciation limit was resolved. T ~ 4 mK v’ : vibrational number counted from the dissociation limit.

  21. 174Yb v’ = 10 Je = 3 176Yb Je = 1 RC=17.4 nm Je = 3 v’ = 10 Je = 1 RC=15.1 nm v’ = 14 RC=8.6 nm Je = 3 Je = 1 v’ = 13 Je = 3 RC= 9.0 nm Je = 1 v’ = 16 RC=6.5 nm Je = 1 Je= 3 v’ = 16 Je= 3 RC= 6.0 nm Je = 1 Large difference in signal intensity PA spectra of 174Yb & 176Yb (T~25K)

  22. wavefunction near shape resonance wavefunction far from shape resonance d-wave potential The PA efficiency for Je=3 line of 174Yb is large inside the centri- fugal potential barrier. This is due to shape resonance. Difference between 174Yb & 176Yb

  23. T  L F S I Ja Intercombination PAS of fermionic (i0) isotopes (171Yb, 173Yb ) hyperfine coupling coupling to molecular axis

  24. j 1S0, f1=1/2 i Potential calculation f 171Yb (3P1) ‥ i=1/2, j=1 i (1S0) ‥ i=1/2, j=0 3P1, f2=3/2,1/2 basis sym.: basis antisym.: , , iand  are projection of and to molecular axis, respectively. , :transition dipole, a:hyperfine coupling constant

  25. p,f-wave s,d-wave Pair potential of 171Yb2 [1S0+3P1(f=3/2)] f=3/2 f=3/2 F = 1 F = 2,F = 0 F = 2 F = 1,F = 0 F = 1 statesym.: stateantisym.: Hyperfine-induced purely long-range states exist.

  26. -1000 -400 -200 0 (MHz) -800 -600 f =3/2 -1060MHz ~ -160MHz PA spectrum of 171Yb Temperature ~20 K T=1 T=2 s p T=3 p T=1 s wave p wave purely long-range state

  27. PAS with the intercombination transition Conclusion d-wave shape resonance is inferred for 174Yb. Hyperfine-induced purely long-range state was observed. PAS with the dipole-allowed transition a = 5.53 ± 0.11 nm, C6 = 2300 ± 250 nm for 174Yb Two-color PAS of 174Yb Bound levels at 10.6 MHz and 268.6 MHz were found. Optical Feshbach resonance with the intercombination line The asymmetric spectrum implies the change of a. 3P2 state atoms are trapped in the optical trap with high density. Quantum degenerate gases have been achieved for 5 isotopes.

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