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Laser cooling of a diatomic molecule

Nature volume 467, pages 820–823 (2010)Cite this article

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Abstract

It has been roughly three decades since laser cooling techniques produced ultracold atoms1,2,3, leading to rapid advances in a wide array of fields. Laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for a wide range of applications4. For example, heteronuclear molecules possess permanent electric dipole moments that lead to long-range, tunable, anisotropic dipole–dipole interactions. The combination of the dipole–dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures makes ultracold molecules attractive candidates for use in quantum simulations of condensed-matter systems5 and in quantum computation6. Also, ultracold molecules could provide unique opportunities for studying chemical dynamics7,8 and for tests of fundamental symmetries9,10,11. Here we experimentally demonstrate laser cooling of the polar molecule strontium monofluoride (SrF). Using an optical cycling scheme requiring only three lasers12, we have observed both Sisyphus and Doppler cooling forces that reduce the transverse temperature of a SrF molecular beam substantially, to a few millikelvin or less. At present, the only technique for producing ultracold molecules is to bind together ultracold alkali atoms through Feshbach resonance13 or photoassociation14. However, proposed applications for ultracold molecules require a variety of molecular energy-level structures (for example unpaired electronic spin5,9,11,15, Omega doublets16 and so on). Our method provides an alternative route to ultracold molecules. In particular, it bridges the gap between ultracold (submillikelvin) temperatures and the ∼1-K temperatures attainable with directly cooled molecules (for example with cryogenic buffer-gas cooling17 or decelerated supersonic beams18). Ultimately, our technique should allow the production of large samples of molecules at ultracold temperatures for species that are chemically distinct from bialkalis.

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Figure 1: Energy-level structure in SrF.
Figure 2: Laser cooling of SrF.
Figure 3: Magnetic field and frequency dependence of the cooling forces.

References

  1. Chu, S. The manipulation of neutral particles. Rev. Mod. Phys. 70, 685–706 (1998)

    Article  ADS  CAS  Google Scholar 

  2. Cohen-Tannoudji, C. N. Manipulating atoms with photons. Rev. Mod. Phys. 70, 707–719 (1998)

    Article  ADS  CAS  Google Scholar 

  3. Phillips, W. D. Laser cooling and trapping of neutral atoms. Rev. Mod. Phys. 70, 721–741 (1998)

    Article  ADS  CAS  Google Scholar 

  4. Carr, L., DeMille, D., Krems, R. & Ye, J. Cold and ultracold molecules: science, technology and applications. N. J. Phys. 11, 055049 (2009)

    Article  Google Scholar 

  5. Pupillo, G. Micheli, A., Büchler, H.-P. & Zoller, P. in Cold Molecules: Theory, Experiment, Applications (eds Krems, R., Friedrich, B. & Stwalley, W. C.) Ch. 12 (CRC Press, 2009)

    Google Scholar 

  6. DeMille, D. Quantum computation with trapped polar molecules. Phys. Rev. Lett. 88, 067901 (2002)

    Article  ADS  CAS  Google Scholar 

  7. Balakrishnan, N. & Dalgarno, A. Chemistry at ultracold temperatures. Chem. Phys. Lett. 341, 652–656 (2001)

    Article  ADS  CAS  Google Scholar 

  8. Krems, R. V. Cold controlled chemistry. Phys. Chem. Chem. Phys. 10, 4079–4092 (2008)

    Article  CAS  Google Scholar 

  9. Tarbutt, M., Hudson, J., Sauer, B. & Hinds, E. Prospects for measuring the electric dipole moment of the electron using electrically trapped polar molecules. Faraday Discuss. 142, 37–56 (2009)

    Article  ADS  CAS  Google Scholar 

  10. Flambaum, V. V. & Kozlov, M. G. Enhanced sensitivity to the time variation of the fine-structure constant and m p /m e in diatomic molecules. Phys. Rev. Lett. 99, 150801 (2007)

    Article  ADS  CAS  Google Scholar 

  11. DeMille, D., Cahn, S. B., Murphree, D., Rahmlow, D. A. & Kozlov, M. G. Using molecules to measure nuclear spin-dependent parity violation. Phys. Rev. Lett. 100, 023003 (2008)

    Article  ADS  CAS  Google Scholar 

  12. Shuman, E. S., Barry, J. F., Glenn, D. R. & DeMille, D. Radiative force from optical cycling on a diatomic molecule. Phys. Rev. Lett. 103, 223001 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Ni, K.-K. et al. A high phase-space-density gas of polar molecules. Science 322, 231–235 (2008)

    Article  ADS  CAS  Google Scholar 

  14. Sage, J. M., Sainis, S., Bergeman, T. & DeMille, D. Optical production of ultracold polar molecules. Phys. Rev. Lett. 94, 203001 (2005)

    Article  ADS  Google Scholar 

  15. André, A. et al. A coherent all-electrical interface between polar molecules and mesoscopic superconducting resonators. Nature Phys. 2, 636–642 (2006)

    Article  ADS  Google Scholar 

  16. Vutha, A. C. et al. Search for the electric dipole moment of the electron with thorium monoxide. J. Phys. At. Mol. Opt. Phys. 43, 074007 (2010)

    Article  ADS  Google Scholar 

  17. Weinstein, J. D., deCarvalho, R., Guillet, T., Friedrich, B. & Doyle, J. M. Magnetic trapping of calcium monohydride molecules at millikelvin temperatures. Nature 395, 148–150 (1998)

    Article  ADS  CAS  Google Scholar 

  18. Bethlem, H. L. et al. Electrostatic trapping of ammonia molecules. Nature 406, 491–494 (2000)

    Article  ADS  CAS  Google Scholar 

  19. Maxwell, S. E. et al. High-flux beam source for cold, slow atoms or molecules. Phys. Rev. Lett. 95, 173201 (2005)

    Article  ADS  CAS  Google Scholar 

  20. Patterson, D. & Doyle, J. M. Bright, guided molecular beam with hydrodynamic enhancement. J. Chem. Phys. 126, 154307 (2007)

    Article  ADS  Google Scholar 

  21. Allouche, A. R., Wannous, G. & Aubért-Frecon, M. A ligand-field approach for the low-lying states of Ca, Sr and Ba monohalides. Chem. Phys. 170, 11–22 (1993)

    Article  CAS  Google Scholar 

  22. Dagdigian, P. J., Cruse, H. W. & Zare, R. N. Radiative lifetimes of the alkaline earth monohalides. J. Chem. Phys. 60, 2330–2339 (1974)

    Article  ADS  CAS  Google Scholar 

  23. Di Rosa, M. D. Laser-cooling molecules. Eur. Phys. J. D 31, 395–402 (2004)

    Article  ADS  Google Scholar 

  24. Stuhl, B. K., Sawyer, B. C., Wang, D. & Ye, J. A magneto-optical trap for polar molecules. Phys. Rev. Lett. 101, 243002 (2008)

    Article  ADS  Google Scholar 

  25. Berkeland, D. J. & Boshier, M. G. Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems. Phys. Rev. A 65, 033413 (2002)

    Article  ADS  Google Scholar 

  26. Emile, O. et al. Magnetically assisted Sisyphus effect. J. Phys. II Fr. 3, 1709–1733 (1993)

    CAS  Google Scholar 

  27. Gupta, R., Padua, S., Xie, C., Batelaan, H. & Metcalf, H. Simplest atomic system for sub-Doppler laser cooling. J. Opt. Soc. Am. B 11, 537–541 (1994)

    Article  ADS  CAS  Google Scholar 

  28. Plimmer, M. D. et al. 2D laser collimation of a cold Cs beam induced by a transverse B field. JETP Lett. 82, 17–21 (2005)

    Article  ADS  CAS  Google Scholar 

  29. Childs, W. J., Goodman, L. S. & Renhorn, I. Radio-frequency optical double-resonance spectrum of SrF: the X2Σ+ state. J. Mol. Spectrosc. 87, 522–533 (1981)

    Article  ADS  CAS  Google Scholar 

  30. Kändler, J., Martell, T. & Ernst, W. Electric dipole moments and hyperfine structure of SrF A2Π and B2Σ+ . Chem. Phys. Lett. 155, 470–474 (1989)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This material is based upon work supported by the ARO, the NSF and the AFOSR under the MURI award FA9550-09-1-0588.

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Authors and Affiliations

  1. Department of Physics, Yale University, PO Box 208120, New Haven, Connecticut 06520, USA,

    E. S. Shuman, J. F. Barry & D. DeMille

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  1. E. S. Shuman
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  2. J. F. Barry
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  3. D. DeMille
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Contributions

The experimental work, data analysis and theoretical calculations were performed by E.S.S., J.F.B. and D.D.

Corresponding author

Correspondence to E. S. Shuman.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Information comprising Experimental set-up, Capture velocity and optimum magnetic field for Sisyphus and Doppler forces, Estimation of temperature and power of Sisyphus and Doppler cooling. Also included are Supplementary Figures 1-4 with legends. (PDF 249 kb)

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Shuman, E., Barry, J. & DeMille, D. Laser cooling of a diatomic molecule. Nature 467, 820–823 (2010). https://doi.org/10.1038/nature09443

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