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.

  • Letter
  • Published:

Probable observation of a supersolid helium phase

Abstract

When liquid 4He is cooled below 2.176 K, it undergoes a phase transition—Bose–Einstein condensation—and becomes a superfluid with zero viscosity1. Once in such a state, it can flow without dissipation even through pores of atomic dimensions. Although it is intuitive to associate superflow only with the liquid phase2, it has been proposed theoretically3,4,5 that superflow can also occur in the solid phase of 4He. Owing to quantum mechanical fluctuations, delocalized vacancies and defects are expected to be present in crystalline solid 4He, even in the limit of zero temperature. These zero-point vacancies can in principle allow the appearance of superfluidity in the solid3,4. However, in spite of many attempts6, such a ‘supersolid’ phase has yet to be observed in bulk solid 4He. Here we report torsional oscillator measurements on solid helium confined in a porous medium, a configuration that is likely to be more heavily populated with vacancies than bulk helium. We find an abrupt drop in the rotational inertia5 of the confined solid below a certain critical temperature. The most likely interpretation of the inertia drop is entry into the supersolid phase. If confirmed, our results show that all three states of matter—gas7, liquid1 and solid—can undergo Bose–Einstein condensation.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Torsional oscillator used in this experiment.
Figure 2: Resonant period as function of temperature of solid 4He in Vycor glass.
Figure 3: ΔP at the low temperature limit, ΔP0, as a function of rim velocity of the Vycor disk. ΔP0 values are deduced by subtracting the measured periods at 30 mK from the (shifted) empty cell period, as shown in Fig. 2.
Figure 4: Resonant periods as a function of temperature for a variety of solid helium samples.

Similar content being viewed by others

References

  1. Kapitza, P. Viscosity of liquid helium below the λ-point. Nature 141, 74 (1938)

    Article  ADS  CAS  Google Scholar 

  2. Penrose, O. & Onsager, L. Bose-Einstein condensation and liquid helium. Phys. Rev. 104, 576–584 (1956)

    Article  ADS  CAS  Google Scholar 

  3. Andreev, A. F. & Lifshitz, I. M. Quantum theory of defects in crystals. Sov. Phys. JETP 29, 1107–1113 (1969)

    ADS  Google Scholar 

  4. Chester, G. V. Speculations on Bose-Einstein condensation and quantum crystals. Phys. Rev. A 2, 256–258 (1970)

    Article  ADS  Google Scholar 

  5. Leggett, A. J. Can a solid be “superfluid”? Phys. Rev. Lett. 25, 1543–1546 (1970)

    Article  ADS  CAS  Google Scholar 

  6. Meisel, M. W. Supersolid 4He—An overview of past searches and future possibilities. Physica B 178, 121–128 (1992)

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  PubMed  Google Scholar 

  8. Bishop, D. J., Paalanen, M. A. & Reppy, J. D. Search for superfluidity in hcp 4He. Phys. Rev. B 24, 2844–2845 (1981)

    Article  ADS  CAS  Google Scholar 

  9. Levitz, P., Ehret, G., Sinha, S. K. & Drake, J. M. Porous Vycor glass—the micro structure as probed by electron-microscopy, direct energy-transfer, small-angle scattering, and molecular adsorption. J. Chem. Phys. 95, 6151–6161 (1991)

    Article  ADS  CAS  Google Scholar 

  10. Brewer, D. F., Cao, L., Girit, C. & Reppy, J. D. 4He transition in a restricted geometry below and above the bulk solidification pressure. Physica B 107, 583–584 (1981)

    Article  CAS  Google Scholar 

  11. Cao, L., Brewer, D. F., Girit, C., Smith, E. N. & Reppy, J. D. Flow and torsional oscillator measurements on liquid helium in restricted geometries under pressure. Phys. Rev. B 33, 106–117 (1986)

    Article  ADS  CAS  Google Scholar 

  12. Beamish, J. R., Hikata, A., Tell, L. & Elbaum, C. Solidification and superfluidity of 4He in porous Vycor glass. Phys. Rev. Lett. 50, 425–428 (1983)

    Article  ADS  CAS  Google Scholar 

  13. Molz, E. B. & Beamish, J. R. Freezing and melting of helium in different porous media. J. Low-Temp. Phys. 101, 1055–1077 (1995)

    Article  ADS  CAS  Google Scholar 

  14. Adams, E. D., Uhlig, K., Tang, Y. H. & Haas, G. E. Solidification and superfluidity of 4He in confined geometries. Phys. Rev. Lett. 52, 2249–2252 (1984)

    Article  ADS  CAS  Google Scholar 

  15. Bittner, D. N. & Adams, E. D. Solidification of helium in confined geometries. J. Low-Temp. Phys. 97, 519–535 (1994)

    Article  ADS  CAS  Google Scholar 

  16. Chan, M. H. W., Yanof, A. W. & Reppy, J. D. Superfluidity of thin 4He films. Phys. Rev. Lett. 32, 1347–1350 (1974)

    Article  ADS  Google Scholar 

  17. Mehl, J. B. & Zimmermann, W. Jr Flow of superfluid helium in a porous medium. Phys. Rev. 167, 214–229 (1968)

    Article  ADS  CAS  Google Scholar 

  18. Berthold, J. E., Bishop, D. J. & Reppy, J. D. Superfluid transition of 4He films adsorbed on porous Vycor glass. Phys. Rev. Lett. 39, 348–352 (1977)

    Article  ADS  CAS  Google Scholar 

  19. Huang, K. Statistical Mechanics 2nd edn, 293 (Wiley & Son, New York, 1967)

    Google Scholar 

  20. Palaanen, M. A., Bishop, D. J. & Dail, H. W. Dislocation motion in hcp 4He. Phys. Rev. Lett. 46, 664–667 (1981)

    Article  ADS  Google Scholar 

  21. Csáthy, G. A. & Chan, M. H. W. Effect of 3He on submonolayer superfluidity. Phys. Rev. Lett. 87, 045301 (2001)

    Article  ADS  PubMed  Google Scholar 

Download references

Acknowledgements

We acknowledge discussions with J. Banavar, J. Beamish, V. Crespi, J. Goodkind, J. Jain, A. Leggett and J. Reppy. This work was supported by the Condensed Matter Physics Program of the National Science Foundation.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to M. H. W. Chan.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kim, E., Chan, M. Probable observation of a supersolid helium phase. Nature 427, 225–227 (2004). https://doi.org/10.1038/nature02220

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature02220

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

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