Letter | Published:

Continuous-wave room-temperature diamond maser

Nature volume 555, pages 493496 (22 March 2018) | Download Citation


The maser—the microwave progenitor of the optical laser—has been confined to relative obscurity owing to its reliance on cryogenic refrigeration and high-vacuum systems. Despite this, it has found application in deep-space communications and radio astronomy owing to its unparalleled performance as a low-noise amplifier and oscillator. The recent demonstration of a room-temperature solid-state maser that utilizes polarized electron populations within the triplet states of photo-excited pentacene molecules in a p-terphenyl host1,2,3 paves the way for a new class of maser. However, p-terphenyl has poor thermal and mechanical properties, and the decay rates of the triplet sublevel of pentacene mean that only pulsed maser operation has been observed in this system. Alternative materials are therefore required to achieve continuous emission: inorganic materials that contain spin defects, such as diamond4,5,6 and silicon carbide7, have been proposed. Here we report a continuous-wave room-temperature maser oscillator using optically pumped nitrogen–vacancy defect centres in diamond. This demonstration highlights the potential of room-temperature solid-state masers for use in a new generation of microwave devices that could find application in medicine, security, sensing and quantum technologies.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    , & Room-temperature solid-state maser. Nature 488, 353–356 (2012)

  2. 2.

    et al. Enhanced magnetic Purcell effect in room-temperature masers. Nat. Commun. 6, 6215 (2015)

  3. 3.

    et al. Nanosecond time-resolved characterization of a pentacene-based room-temperature maser. Sci. Rep. 7, 41836 (2017)

  4. 4.

    , & Inverted EPR signal from nitrogen defects in a synthetic diamond single crystal at room temperature. JETP Lett. 80, 748–751 (2004)

  5. 5.

    et al. Nitrogen-doped chemical vapour deposited diamond: a new material for room-temperature solid state maser. Chin. Phys. Lett. 24, 2088–2090 (2007)

  6. 6.

    et al. Proposal for a room-temperature diamond maser. Nat. Commun. 6, 8251 (2015)

  7. 7.

    et al. Room-temperature quantum microwave emitters based on spin defects in silicon carbide. Nat. Phys. 10, 157–162 (2014)

  8. 8.

    , , & Electron-spin resonance of nitrogen donors in diamond. Phys. Rev. 115, 1546–1552 (1959)

  9. 9.

    , & Cross relaxation studies in diamond. Phys. Rev. 118, 939–945 (1960)

  10. 10.

    Microwave Solid-State Masers Ch. 4 (McGraw-Hill, 1964).

  11. 11.

    & Electron spin resonance in the study of diamond. Rep. Prog. Phys. 41, 1201–1248 (1978)

  12. 12.

    et al. Scanning confocal optical microscopy and magnetic resonance on single defect centers. Science 276, 2012–2014 (1997)

  13. 13.

    et al. High-sensitivity diamond magnetometer with nanoscale resolution. Nat. Phys. 4, 810–816 (2008); erratum 7, 270 (2011)

  14. 14.

    et al. Nanoscale magnetic sensing with an individual electronic spin in diamond. Nature 455, 644–647 (2008)

  15. 15.

    et al. Coherent dynamics of coupled electron and nuclear spin qubits in diamond. Science 314, 281–285 (2006)

  16. 16.

    , , , & Quenching spin decoherence in diamond through spin bath polarization. Phys. Rev. Lett. 101, 047601 (2008)

  17. 17.

    , , , & Temperature- and magnetic-field-dependent longitudinal spin relaxation in nitrogen-vacancy ensembles in diamond. Phys. Rev. Lett. 108, 197601 (2012)

  18. 18.

    , , & Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond. New J. Phys. 13, 025013 (2011)

  19. 19.

    et al. The nitrogen-vacancy colour centre in diamond. Phys. Rep. 528, 1–45 (2013)

  20. 20.

    et al. Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states. npj Quantum Inf. 3, 1 (2017)

  21. 21.

    & Infrared and optical masers. Phys. Rev. 112, 1940–1949 (1958)

  22. 22.

    , , & Proposed realization of the Dicke-model quantum phase transition in an optical cavity QED system. Phys. Rev. A 75, 013804 (2007)

  23. 23.

    , & High-frequency pulsed endor spectroscopy of the NV centre in the commercial HPHT diamond. J. Magn. Reson. 262, 15–19 (2016)

  24. 24.

    & Exact solution for an N-molecule radiation-field Hamiltonian. Phys. Rev. 170, 379–384 (1968)

  25. 25.

    Statistical Methods in Quantum Optics 1: Master Equations and Fokker-Planck Equations Ch. 7 (Springer, 2003)

  26. 26.

    & Photo-ionization of the nitrogen-vacancy center in diamond. Diamond Related Materials 14, 1705–1710 (2005)

  27. 27.

    , , , & Photo-induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single-shot charge state detection. New J. Phys. 15, 013064 (2013)

  28. 28.

    & Dielectric Resonators 1st edn, Ch. 5 (Artech House, 1964)

  29. 29.

    et al. Two-photon excited fluorescence of nitrogen-vacancy centers in proton-irradiated type Ib diamond. J. Phys. Chem. A 111, 9379–9386 (2007)

Download references


We thank J. Hall and M. Markham (Element 6 Ltd) for supplying the diamond samples, P. French and R. Taylor (Photonics Group at Imperial College London) for lending us their continuous-wave laser, and E. Bauch (Harvard University) for discussions. We also thank M. Lennon (IC), D. Halpin and D. Farquharson (UCL) for manufacturing the cavity components. This work was supported by the UK Engineering and Physical Sciences Research Council through grants EP/K011987/1 (IC) and EP/K011804/1 (UCL). We also acknowledge support from the Henry Royce Institute.

Author information


  1. Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK

    • Jonathan D. Breeze
    • , Juna Sathian
    •  & Neil McN. Alford
  2. London Centre for Nanotechnology, Imperial College London, Exhibition Road, London SW7 2AZ, UK

    • Jonathan D. Breeze
    •  & Neil McN. Alford
  3. Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 8BT, UK

    • Enrico Salvadori
    •  & Christopher W. M. Kay
  4. London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH, UK

    • Enrico Salvadori
    •  & Christopher W. M. Kay
  5. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK

    • Enrico Salvadori
  6. Department of Chemistry, University of Saarland, 66123 Saarbrücken, Germany

    • Christopher W. M. Kay


  1. Search for Jonathan D. Breeze in:

  2. Search for Enrico Salvadori in:

  3. Search for Juna Sathian in:

  4. Search for Neil McN. Alford in:

  5. Search for Christopher W. M. Kay in:


J.D.B. conceived the study, developed the theory, designed the maser cavity, devised the experiment and wrote software for collecting experimental data. J.D.B. and C.W.M.K. developed the experimental design and performed experiments with input from E.S. and J.S. J.D.B. interpreted the results with input from E.S. and C.W.M.K. J.S. characterized the diamond NV concentration by optical means and developed the optical pumping scheme. J.D.B., E.S. and C.W.M.K. characterized the diamonds using EPR. J.D.B. wrote the paper with assistance from C.W.M.K. and with additional editing by E.S. and N.M.A.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jonathan D. Breeze.

Reviewer Information Nature thanks A. Blank, F. Jelezko and R.-B. Liu for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

About this article

Publication history






Further reading


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.