Letter | Published:

Observation of Dirac monopoles in a synthetic magnetic field

Nature volume 505, pages 657660 (30 January 2014) | Download Citation

Abstract

Magnetic monopoles—particles that behave as isolated north or south magnetic poles—have been the subject of speculation since the first detailed observations of magnetism several hundred years ago1. Numerous theoretical investigations and hitherto unsuccessful experimental searches2 have followed Dirac’s 1931 development of a theory of monopoles consistent with both quantum mechanics and the gauge invariance of the electromagnetic field3. The existence of even a single Dirac magnetic monopole would have far-reaching physical consequences, most famously explaining the quantization of electric charge3,4. Although analogues of magnetic monopoles have been found in exotic spin ices5,6 and other systems7,8,9, there has been no direct experimental observation of Dirac monopoles within a medium described by a quantum field, such as superfluid helium-3 (refs 10, 11, 12, 13). Here we demonstrate the controlled creation14 of Dirac monopoles in the synthetic magnetic field produced by a spinor Bose–Einstein condensate. Monopoles are identified, in both experiments and matching numerical simulations, at the termini of vortex lines within the condensate. By directly imaging such a vortex line, the presence of a monopole may be discerned from the experimental data alone. These real-space images provide conclusive and long-awaited experimental evidence of the existence of Dirac monopoles. Our result provides an unprecedented opportunity to observe and manipulate these quantum mechanical entities in a controlled environment.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    , , eds. Magnetic Monopoles (American Association of Physics Teachers, 1990)

  2. 2.

    Theoretical and experimental status of magnetic monopoles. Rep. Prog. Phys. 69, 1637–1711 (2006)

  3. 3.

    Quantised singularities in the electromagnetic field. Proc. R. Soc. Lond. A 133, 60–72 (1931)

  4. 4.

    , , eds. Cosmic Strings and Other Topological Defects (Cambridge Univ. Press, 1994)

  5. 5.

    , & Magnetic monopoles in spin ice. Nature 451, 42–45 (2008)

  6. 6.

    et al. Dirac strings and magnetic monopoles in the spin ice Dy2Ti2O7. Science 326, 411–414 (2009)

  7. 7.

    , , & Cosmology in the laboratory: defect dynamics in liquid crystals. Science 251, 1336–1342 (1991)

  8. 8.

    et al. The anomalous Hall effect and magnetic monopoles in momentum space. Science 302, 92–95 (2003)

  9. 9.

    et al. Unwinding of a skyrmion lattice by magnetic monopoles. Science 340, 1076–1080 (2013)

  10. 10.

    Quantization rules for point singularities in superfluid 3He and liquid crystals. Phys. Rev. Lett. 36, 874–876 (1976)

  11. 11.

    & Vortices with free ends in superfluid He3-A. JETP Lett. 23, 647–649 (1976)

  12. 12.

    Monopoles in the rotating superfluid helium-3 A–B interface. Nature 326, 367–370 (1987)

  13. 13.

    The Universe in a Helium Droplet 214–217 (Oxford Univ. Press, 2003)

  14. 14.

    & Creation of Dirac monopoles in spinor Bose-Einstein condensates. Phys. Rev. Lett. 103, 030401 (2009)

  15. 15.

    , , , & Synthetic magnetic fields for ultracold neutral atoms. Nature 462, 628–631 (2009)

  16. 16.

    , , & Artificial gauge potentials for neutral atoms. Rev. Mod. Phys. 83, 1523–1543 (2011)

  17. 17.

    & Dirac monopoles and dipoles in ferromagnetic spinor Bose-Einstein condensates. Phys. Rev. A 68, 043604 (2003)

  18. 18.

    et al. Imprinting vortices in a Bose-Einstein condensate using topological phases. Phys. Rev. Lett. 89, 190403 (2002)

  19. 19.

    , & Observation of topologically stable 2D skyrmions in an antiferromagnetic spinor Bose-Einstein condensate. Phys. Rev. Lett. 108, 035301 (2012)

  20. 20.

    & Concept of nonintegrable phase factors and global formulation of gauge fields. Phys. Rev. D 12, 3845–3857 (1975)

  21. 21.

    et al. Radio-frequency dressing of multiple Feshbach resonances. Phys. Rev. A 80, 050701 (2009)

  22. 22.

    et al. Dynamical instability of a doubly quantized vortex in a Bose-Einstein condensate. Phys. Rev. Lett. 93, 160406 (2004)

  23. 23.

    First results from a superconductive detector for moving magnetic monopoles. Phys. Rev. Lett. 48, 1378–1381 (1982)

  24. 24.

    , & Ground-state Dirac monopole. Phys. Rev. A 84, 063627 (2011)

  25. 25.

    & Non-Abelian magnetic monopole in a Bose-Einstein condensate. Phys. Rev. Lett. 102, 080403 (2009)

  26. 26.

    , & Vortex pump for dilute Bose-Einstein condensates. Phys. Rev. Lett. 99, 250406 (2007)

  27. 27.

    , & From rotating atomic rings to quantum Hall states. Sci. Rep. 1, 43 (2011)

  28. 28.

    et al. Observation of a geometric Hall effect in a spinor Bose-Einstein condensate with a skyrmion spin texture. Phys. Rev. Lett. 111, 245301 (2013)

  29. 29.

    & Further generalization of Landau-Zener calculation. J. Opt. Soc. Am. B 2, 1355–1360 (1985)

Download references

Acknowledgements

We acknowledge funding by the National Science Foundation (grants PHY–0855475 and PHY–1205822), by the Academy of Finland through its Centres of Excellence Program (grant no. 251748) and grants (nos 135794, 272806 and 141015), and the Finnish Doctoral Programme in Computational Sciences. CSC – IT Center for Science Ltd is acknowledged for computational resources (project no. ay2090). We thank G. Volovik, M. Krusius, R. H. Romer, M. Nakahara and J. R. Friedman for their comments on the manuscript. We also thank H. Valja for his artistic input. M.W.R. and D.S.H. acknowledge discussions with R. P. Anderson and K. Jagannathan, and experimental assistance from N. B. Bern.

Author information

Author notes

    • S. Kandel

    Present address: City of Hope National Medical Center, 1500 East Duarte Road, Duarte, California 91010, USA.

Affiliations

  1. Department of Physics, Amherst College, Amherst, Massachusetts 01002–5000, USA

    • M. W. Ray
    • , S. Kandel
    •  & D. S. Hall
  2. QCD Labs, COMP Centre of Excellence, Department of Applied Physics, Aalto University, PO Box 13500, 00076 Aalto, Finland

    • E. Ruokokoski
    •  & M. Möttönen
  3. Low Temperature Laboratory (OVLL), Aalto University, PO Box 13500, 00076 Aalto, Finland

    • M. Möttönen

Authors

  1. Search for M. W. Ray in:

  2. Search for E. Ruokokoski in:

  3. Search for S. Kandel in:

  4. Search for M. Möttönen in:

  5. Search for D. S. Hall in:

Contributions

M.W.R., S.K. and D.S.H. developed and conducted the experiments, after which M.W.R. and D.S.H. analysed the data. E.R. performed the numerical simulations under the guidance of M.M., who also developed the gauge transformations presented in Supplementary Information. Interactive feedback between the experiments and simulations carried out by M.W.R., D.S.H., E.R. and M.M. was essential to achieving the reported results. All authors discussed both experimental and theoretical results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to D. S. Hall.

Extended data

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Text and Supplementary Figure 1 providing additional information regarding the underlying theory of the system.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature12954

Further reading

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.