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Evaporative cooling of the dipolar hydroxyl radical

Abstract

Atomic physics was revolutionized by the development of forced evaporative cooling, which led directly to the observation of Bose–Einstein condensation1,2, quantum-degenerate Fermi gases3 and ultracold optical lattice simulations of condensed-matter phenomena4. More recently, substantial progress has been made in the production of cold molecular gases5. Their permanent electric dipole moment is expected to generate systems with varied and controllable phases6,7,8, dynamics9,10,11 and chemistry12,13,14. However, although advances have been made15 in both direct cooling and cold-association techniques, evaporative cooling has not been achieved so far. This is due to unfavourable ratios of elastic to inelastic scattering13 and impractically slow thermalization rates in the available trapped species. Here we report the observation of microwave-forced evaporative cooling of neutral hydroxyl (OH) molecules loaded from a Stark-decelerated beam into an extremely high-gradient magnetic quadrupole trap. We demonstrate cooling by at least one order of magnitude in temperature, and a corresponding increase in phase-space density by three orders of magnitude, limited only by the low-temperature sensitivity of our spectroscopic thermometry technique. With evaporative cooling and a sufficiently large initial population, much colder temperatures are possible; even a quantum-degenerate gas of this dipolar radical (or anything else it can sympathetically cool) may be within reach.

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Figure 1: Ground-state structure and scattering theory of OH.
Figure 2: Trap system and inelastic collisions.
Figure 3: Microwave spectra illustrating six different final temperatures.
Figure 4: Scaling relations observed in the evaporative cooling of OH.

References

  1. 1

    Anderson, M. H., Ensher, J. R., Matthews, M. R., Wieman, C. E. & Cornell, E. A. Observation of Bose-Einstein condensation in a dilute atomic vapor. Science 269, 198–201 (1995)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Davis, K. B. et al. Bose-Einstein condensation in a gas of sodium atoms. Phys. Rev. Lett. 75, 3969–3973 (1995)

    ADS  CAS  Article  Google Scholar 

  3. 3

    DeMarco, B. & Jin, D. S. Onset of Fermi degeneracy in a trapped atomic gas. Science 285, 1703–1706 (1999)

    CAS  Article  Google Scholar 

  4. 4

    Bakr, W. S. et al. Probing the superfluid-to-Mott insulator transition at the single-atom level. Science 329, 547–550 (2010)

    ADS  CAS  Article  Google Scholar 

  5. 5

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

    ADS  CAS  Article  Google Scholar 

  6. 6

    Pupillo, G. et al. Cold atoms and molecules in self-assembled dipolar lattices. Phys. Rev. Lett. 100, 050402 (2008)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Baranov, M. A., Micheli, A., Ronen, S. & Zoller, P. Bilayer superfluidity of fermionic polar molecules: many-body effects. Phys. Rev. A 83, 043602 (2011)

    ADS  Article  Google Scholar 

  8. 8

    Levinsen, J., Cooper, N. R. & Shlyapnikov, G. V. Topological p x +ip y superfluid phase of fermionic polar molecules. Phys. Rev. A 84, 013603 (2011)

    ADS  Article  Google Scholar 

  9. 9

    Barnett, R., Petrov, D., Lukin, M. & Demler, E. Quantum magnetism with multicomponent dipolar molecules in an optical lattice. Phys. Rev. Lett. 96, 190401 (2006)

    ADS  Article  Google Scholar 

  10. 10

    Büchler, H. P. et al. Strongly correlated 2D quantum phases with cold polar molecules: controlling the shape of the interaction potential. Phys. Rev. Lett. 98, 060404 (2007)

    ADS  Article  Google Scholar 

  11. 11

    Gorshkov, A. V. et al. Tunable superfluidity and quantum magnetism with ultracold polar molecules. Phys. Rev. Lett. 107, 115301 (2011)

    ADS  Article  Google Scholar 

  12. 12

    Ospelkaus, S. et al. Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules. Science 327, 853–857 (2010)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Ni, K.-K. et al. Dipolar collisions of polar molecules in the quantum regime. Nature 464, 1324–1328 (2010)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Quéméner, G. & Julienne, P. S. Ultracold molecules under control!. Chem. Rev. 112, 4949–5011 (2012)

    Article  Google Scholar 

  15. 15

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

    Article  Google Scholar 

  16. 16

    Ketterle, W. & VanDruten, N. Evaporative cooling of trapped atoms. Adv. At. Mol. Opt. Phys. 37, 181–236 (1996)

    ADS  CAS  Article  Google Scholar 

  17. 17

    Fried, D. G. et al. Bose-Einstein condensation of atomic hydrogen. Phys. Rev. Lett. 81, 3811–3814 (1998)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Doret, S. C., Connolly, C. B., Ketterle, W. & Doyle, J. M. Buffer-gas cooled Bose-Einstein condensate. Phys. Rev. Lett. 103, 103005 (2009)

    ADS  Article  Google Scholar 

  19. 19

    Lara, M., Bohn, J. L., Potter, D. E., Soldan, P. & Hutson, J. M. Ultracold Rb–OH collisions and prospects for sympathetic cooling. Phys. Rev. Lett. 97, 183201 (2006)

    ADS  Article  Google Scholar 

  20. 20

    Żuchowski, P. S. & Hutson, J. M. Low-energy collisions of NH3 and ND3 with ultracold Rb atoms. Phys. Rev. A 79, 062708 (2009)

    ADS  Article  Google Scholar 

  21. 21

    Campbell, W. et al. Mechanism of collisional spin relaxation in 3Σ molecules. Phys. Rev. Lett. 102, 013003 (2009)

    ADS  Article  Google Scholar 

  22. 22

    Parazzoli, L. P., Fitch, N. J., Żuchowski, P. S., Hutson, J. M. & Lewandowski, H. J. Large effects of electric fields on atom-molecule collisions at millikelvin temperatures. Phys. Rev. Lett. 106, 193201 (2011)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Ticknor, C. & Bohn, J. L. Influence of magnetic fields on cold collisions of polar molecules. Phys. Rev. A 71, 022709 (2005)

    ADS  Article  Google Scholar 

  24. 24

    Janssen, L. M. C., Żuchowski, P. S., van der Avoird, A., Groenenboom, G. C. & Hutson, J. M. Cold and ultracold NH-NH collisions in magnetic fields. Phys. Rev. A 83, 022713 (2011)

    ADS  Article  Google Scholar 

  25. 25

    Suleimanov, Y. V., Tscherbul, T. V. & Krems, R. V. Efficient method for quantum calculations of molecule-molecule scattering properties in a magnetic field. J. Chem. Phys. 137, 024103 (2012)

    ADS  Article  Google Scholar 

  26. 26

    Manion, J. A. et al. NIST Chemical Kinetics Database. http://kinetics.nist.gov/ (NIST Standard Reference Database 17, Web version 70, Release 1.4 3, Data version 2008. 12)

  27. 27

    Avdeenkov, A. V. & Bohn, J. L. Collisional dynamics of ultracold OH molecules in an electrostatic field. Phys. Rev. A 66, 052718 (2002)

    ADS  Article  Google Scholar 

  28. 28

    Sawyer, B. C., Stuhl, B. K., Wang, D., Yeo, M. & Ye, J. Molecular beam collisions with a magnetically trapped target. Phys. Rev. Lett. 101, 203203 (2008)

    ADS  Article  Google Scholar 

  29. 29

    Child, M. S. Molecular Collision Theory 76 (Dover Publications, 1996)

    Google Scholar 

  30. 30

    Derevianko, A., Johnson, W. R., Safronova, M. S. & Babb, J. F. High-precision calculations of dispersion coefficients, static dipole polarizabilities, and atom-wall interaction constants for alkali-metal atoms. Phys. Rev. Lett. 82, 3589–3592 (1999)

    ADS  CAS  Article  Google Scholar 

  31. 31

    Lev, B. L. et al. OH hyperfine ground state: from precision measurement to molecular qubits. Phys. Rev. A 74, 061402 (2006)

    ADS  Article  Google Scholar 

  32. 32

    Stuhl, B. K., Yeo, M., Sawyer, B. C., Hummon, M. T. & Ye, J. Microwave state transfer and adiabatic dynamics of magnetically trapped polar molecules. Phys. Rev. A 85, 033427 (2012)

    ADS  Article  Google Scholar 

  33. 33

    Bochinski, J. R., Hudson, E. R., Lewandowski, H. J., Meijer, G. & Ye, J. Phase space manipulation of cold free radical OH molecules. Phys. Rev. Lett. 91, 243001 (2003)

    ADS  CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank E. Cornell for discussions and B. Baxley for artistic contributions. We acknowledge funding from the NSF Physics Frontier Center, DOE, AFOSR (MURI), DARPA and NIST.

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Contributions

B.K.S., M.T.H., M.Y. and J.Y. designed and participated in the experiment, and discussed and interpreted the results. B.K.S. ran the day-to-day experiment and collected all the data. G.Q. and J.L.B. constructed the theory. B.K.S. and J.Y. first outlined the manuscript, and B.K.S. and G.Q. wrote the first draft. All authors discussed the results and contributed to the preparation of the manuscript.

Corresponding author

Correspondence to Jun Ye.

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The authors declare no competing financial interests.

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Stuhl, B., Hummon, M., Yeo, M. et al. Evaporative cooling of the dipolar hydroxyl radical. Nature 492, 396–400 (2012). https://doi.org/10.1038/nature11718

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