Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Demagnetization cooling of a gas

Abstract

Adiabatic demagnetization is an efficient technique for cooling solid samples by several orders of magnitude in a single cooling step. In gases, the required coupling between dipolar moments and motion is typically too weak, but in dipolar gases—of high-spin atoms or heteronuclear molecules with strong electric dipole moments, for example—the method should be applicable. Here, we demonstrate demagnetization cooling of a gas of ultracold 52Cr atoms. Demagnetization is driven by inelastic dipolar collisions, which couple the motional degrees of freedom to the spin degree. In this way, kinetic energy is converted into magnetic work, with a consequent temperature reduction of the gas. Optical pumping is used to magnetize the system and drive continuous demagnetization cooling. We can increase the phase-space density of our sample by up to one order of magnitude, with almost no atom loss, suggesting that the method could be used to achieve quantum degeneracy via optical means.

This is a preview of subscription content, access via your institution

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Illustration of demagnetization cooling.
Figure 2: Single-step demagnetization.
Figure 3: Continuous demagnetization cooling.

References

  1. Lounasmaa, O. V. Experimental Principles and Methods Below 1 K (Academic, New York, 1974).

    Google Scholar 

  2. De Haas, W. J., Wiersma, E. C. & Kramers, H. A. Experiments on adiabatic cooling in paramagnetic salts in magnetic fields. Physica 1, 1–13 (1934).

    Article  ADS  Google Scholar 

  3. Kurti, N., Robinson, F. N. H., Simon, F. & Spohr, D. A. Nuclear cooling. Nature 178, 450–453 (1956).

    Article  ADS  Google Scholar 

  4. Oja, A. S. & Lounasmaa, O. V. Nuclear magnetic ordering in simple metals at positive and negative nanokelvin temperatures. Rev. Mod. Phys. 69, 1–136 (1997).

    Article  ADS  Google Scholar 

  5. Touriniemi, J. T. & Knuuttila, T. A. Nuclear cooling and spin properties of rhodium down to picokelvin temperatures. Physica B 280, 474–478 (2000).

    Article  ADS  Google Scholar 

  6. Pecharsky, V. K. & Gschneidner, K. A. Giant magnetocaloric effect in Gd5(Si2Ge2). Phys. Rev. Lett. 78, 4494–4497 (1997).

    Article  ADS  Google Scholar 

  7. Morrish, A. H. The Physical Principles of Magnetism (Wiley, New York, 1983).

    Google Scholar 

  8. Kastler, A. Quelques suggestions concernant la production optique et la détection optique d’une inégalité de population des niveaux de quantification spatiale des atomes. Application à l’expérience de Stern et Gerlach et à la résonance magnétique. J. Phys. Radium 11, 255–265 (1950).

    Article  Google Scholar 

  9. Hänsch, T. W. & Schawlow, A. Cooling of gases by laser radiation. Opt. Commun. 13, 68–69 (1975).

    Article  ADS  Google Scholar 

  10. Hensler, S., Greiner, A., Stuhler, J. & Pfau, T. Depolarisation cooling of an atomic cloud. Europhys. Lett. 71, 918924 (2005).

    Article  Google Scholar 

  11. Hensler, S. et al. Dipolar relaxation in an ultra-cold gas of magnetically trapped chromium atoms. Appl. Phys. B 77, 765–772 (2003).

    Article  ADS  Google Scholar 

  12. Griesmaier, A., Werner, J., Hensler, S., Stuhler, J. & Pfau, T. Bose–Einstein condensation of chromium. Phys. Rev. Lett. 94, 160401 (2005).

    Article  ADS  Google Scholar 

  13. Cohen-Tannoudji, C., Dupont-Roc, J. & Grynberg, G. Atom-Photon Interactions: Basic Processes and Applications 382–383 (Wiley, New York, 1992).

    Google Scholar 

  14. Olshanii, M., Castin, Y. & Dalibard, J. in Proc. 12th Int. Conf. Laser Spectroscopy (eds Inguscio, M., Allegrini, M. & Sasso, A.) 7 (World Scientific, Singapore, 1996).

    Google Scholar 

  15. Castin, Y. & Lewenstein, M. Reabsorption of light by trapped atoms. Phys. Rev. Lett. 80, 5305–5308 (1998).

    Article  ADS  Google Scholar 

  16. Cirac, J. I. & Lewenstein, M. Cooling of atoms in external fields. Phys. Rev. A 52, 4737–4740 (1995).

    Article  ADS  Google Scholar 

  17. Cirac, J. I., Lewenstein, M. & Zoller, P. Collective laser cooling of trapped atoms. Europhys. Lett. 35, 647–651 (1996).

    Article  ADS  Google Scholar 

  18. Lee, H. J., Adams, C. S. & Chu, S. Raman cooling of atoms in an optical dipole trap. Phys. Rev. Lett. 76, 2658–2661 (1996).

    Article  ADS  Google Scholar 

  19. Kerman, A. J., Vuletic, V., Chin, C. & Chu, S. Beyond optical molasses: 3D Raman sideband cooling of atomic cesium to high phase-space density. Phys. Rev. Lett. 84, 439–442 (2000).

    Article  ADS  Google Scholar 

  20. Han, D. J. et al. 3D Raman sideband cooling of cesium atoms at high density. Phys. Rev. Lett. 85, 724–727 (2000).

    Article  ADS  Google Scholar 

  21. Wolf, S., Oliver, S. J. & Weiss, D. S. Suppression of recoil heating by an optical lattice. Phys. Rev. Lett. 85, 4249–4252 (2000).

    Article  ADS  Google Scholar 

  22. Hijmans, T. W. & Burin, A. L. Influence of radiative interatomic collisions on dark-state cooling. Phys. Rev. A 54, 4332–4338 (1996).

    Article  ADS  Google Scholar 

  23. Hancox, C. I., Doret, S. C., Hummon, M. T., Luo, L. & Doyle, J. M. Magnetic trapping of rare-earth atoms at millikelvin temperatures. Nature 431, 281–284 (2004).

    Article  ADS  Google Scholar 

  24. McClelland, J. J. & Hanssen, J. L. Laser cooling without repumping: A magneto-optical trap for erbium atoms. Phys. Rev. Lett. 96, 143005 (2006).

    Article  ADS  Google Scholar 

  25. Friedrich, B. & Herschbach, D. Statistical mechanics of pendular molecules. Int. Rev. Phys. Chem. 15, 325–344 (1996).

    Article  Google Scholar 

Download references

Acknowledgements

We thank our atom optics group for encouragement and practical help. We thank G. J. Beirne for careful reading of the manuscript. This work was supported by the German Science Foundation (DFG) (SPP1116 and SFB/TR 21).

Author information

Authors and Affiliations

Authors

Contributions

M.F., T.K. and S.G. carried out the experimental work and data analysis, A.G. carried out experimental work and S.H., J.S. and T.P. were responsible for project planning.

Corresponding authors

Correspondence to M. Fattori or T. Pfau.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fattori, M., Koch, T., Goetz, S. et al. Demagnetization cooling of a gas. Nature Phys 2, 765–768 (2006). https://doi.org/10.1038/nphys443

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphys443

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing