Experimental constraint on dark matter detection with optical atomic clocks

  • Nature Astronomy 1, Article number: 0009 (2016)
  • doi:10.1038/s41550-016-0009
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The total mass density of the Universe appears to be dominated by dark matter. However, beyond its gravitational interactions at the galactic scale, little is known about its nature1. Several proposals have been advanced in recent years for the detection of dark matter2,​3,​4. In particular, a network of atomic clocks could be used to search for transient indicators of hypothetical dark matter5 in the form of stable topological defects; for example, monopoles, strings or domain walls6. The clocks become desynchronized when a dark-matter object sweeps through the network. This pioneering approach5 requires a comparison between at least two distant optical atomic clocks7,​8,​9. Here, by exploiting differences in the susceptibilities of the atoms and the cavity to the fine-structure constant10,11, we show that a single optical atomic clock12 is already sensitive to dark-matter events. This implies that existing optical atomic clocks13,14 can serve as a global topological-defect dark-matter observatory, without any further developments in experimental apparatus or the need for long phase-noise-compensated optical-fibre links15. Using optical atomic clocks, we explored a new dimension of astrophysical observations by constraining the strength of atomic coupling to hypothetical dark-matter cosmic objects. Under the conditions of our experiments, the degree of constraint was found to exceed the previously reported limits16 by more than three orders of magnitude.

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We are grateful to V. V. Flambaum and Y. V. Stadnik for discussions and crucial remarks concerning the response of an atomic clock transition and an optical cavity to variations in the fine-structure constant, which helped us to properly evaluate our constraints. We also thank W. Ubachs and S. Pustelny for the inspiring discussions. The reported measurements were performed at the National Laboratory FAMO in Toruń, Poland, and were supported by a subsidy from the Polish Ministry of Science and Higher Education. Support has also been received from the project, EMPIR 15SIB03 OC18. This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme. The individual contributors were partially supported by the National Science Centre of Poland through the following projects: 2015/19/D/ST2/02195, DEC-2013/09/N/ST4/00327, 2012/07/B/ST2/00235, DEC-2013/11/D/ST2/02663, 2015/17/B/ST2/02115 and 2014/15/D/ST2/05281. This research was partially supported by the TEAM Programme of the Foundation for Polish Science, which is co-financed by the EU European Regional Development Fund and the COST Action, CM1405 MOLIM. P.W. is supported by the Foundation for Polish Science’s START Programme.

Author information


  1. Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, PL-87-100 Toruń, Poland

    • P. Wcisło
    • , P. Morzyński
    • , M. Bober
    • , A. Cygan
    • , D. Lisak
    • , R. Ciuryło
    •  & M. Zawada


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P.W. developed the concept, performed the calculations and data analysis, and prepared the manuscript. P.M. and M.B. performed the experiment. M.B., P.M., M.Z., D.L., A.C. and R.C. contributed to the development of the experimental setup. P.W., R.C., M.Z., M.B. and P.M. contributed to the interpretation and discussion of the results. R.C., M.Z., D.L., P.M. and M.B. contributed to the preparation of the manuscript. M.Z. leads the experimental group.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to P. Wcisło.