Skip to main content

Thank you for visiting 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.

Observation of strong coupling between a micromechanical resonator and an optical cavity field


Achieving coherent quantum control over massive mechanical resonators is a current research goal. Nano- and micromechanical devices can be coupled to a variety of systems, for example to single electrons by electrostatic1,2 or magnetic coupling3,4, and to photons by radiation pressure5,6,7,8,9 or optical dipole forces10,11. So far, all such experiments have operated in a regime of weak coupling, in which reversible energy exchange between the mechanical device and its coupled partner is suppressed by fast decoherence of the individual systems to their local environments. Controlled quantum experiments are in principle not possible in such a regime, but instead require strong coupling. So far, this has been demonstrated only between microscopic quantum systems, such as atoms and photons (in the context of cavity quantum electrodynamics12) or solid state qubits and photons13,14. Strong coupling is an essential requirement for the preparation of mechanical quantum states, such as squeezed or entangled states15,16,17,18, and also for using mechanical resonators in the context of quantum information processing, for example, as quantum transducers. Here we report the observation of optomechanical normal mode splitting19,20, which provides unambiguous evidence for strong coupling of cavity photons to a mechanical resonator. This paves the way towards full quantum optical control of nano- and micromechanical devices.

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

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Experimental set-up and characterization of the uncoupled mechanical and optical oscillator.
Figure 2: Optomechanical normal mode splitting and avoided crossing in the normal-mode frequency spectrum.


  1. Naik, A. et al. Cooling a nanomechanical resonator with quantum back-action. Nature 443, 193–196 (2006)

    ADS  CAS  Article  Google Scholar 

  2. Cleland, A. N., Aldridge, J. S., Driscoll, D. C. & Gossard, A. C. Nanomechanical displacement sensing using a quantum point contact. Appl. Phys. Lett. 81, 1699–1701 (2002)

    ADS  CAS  Article  Google Scholar 

  3. Rugar, D., Budakian, R., Mamin, H. J. & Chui, B. W. Single spin detection by magnetic resonance force microscopy. Nature 430, 329–332 (2004)

    ADS  CAS  Article  Google Scholar 

  4. Rabl, P. et al. Strong magnetic coupling between an electronic spin qubit and a mechanical resonator. Phys. Rev. B 79, 041302(R) (2009)

    ADS  Article  Google Scholar 

  5. Kippenberg, T. J., Rokhsari, H., Carmon, T., Scherer, A. & Vahala, K. J. Analysis of radiation-pressure induced mechanical oscillation of an optical microcavity. Phys. Rev. Lett. 95, 033901 (2005)

    ADS  CAS  Article  Google Scholar 

  6. Gigan, S. et al. Self-cooling of a micromirror by radiation pressure. Nature 444, 67–71 (2006)

    ADS  CAS  Article  Google Scholar 

  7. Arcizet, O., Cohadon, P.-F., Briant, T., Pinard, M. & Heidmann, A. Radiation-pressure cooling and micromechanical instability of a micromirror. Nature 444, 71–75 (2006)

    ADS  CAS  Article  Google Scholar 

  8. Thompson, J. D. et al. Strong dispersive coupling of a high-finesse cavity to a micromechanical membrane. Nature 452, 72–75 (2008)

    ADS  CAS  Article  Google Scholar 

  9. Regal, C. A., Teufel, J. D. & Lehnert, K. W. Measuring nanomechanical motion with a microwave cavity interferometer. Nature Phys. 4, 555–560 (2008)

    CAS  Article  Google Scholar 

  10. Eichenfield, M., Michael, C. P., Perahia, R. & Painter, O. Actuation of micro-optomechanical systems via cavity-enhanced optical dipole forces. Nature Photon. 1, 416–422 (2007)

    ADS  CAS  Article  Google Scholar 

  11. Li, M. et al. Harnessing optical forces in integrated photonic circuits. Nature 456, 480–484 (2008)

    ADS  CAS  Article  Google Scholar 

  12. Walther, H., Varcoe, B. T. H., Englert, B.-G. & Becker, T. Cavity quantum electrodynamics. Rep. Prog. Phys. 69, 1325–1382 (2006)

    ADS  Article  Google Scholar 

  13. Khitrova, G., Gibbs, H. M., Kira, M., Koch, S. W. & Scherer, A. Vacuum Rabi splitting in semiconductors. Nature Phys. 2, 81–90 (2006)

    ADS  CAS  Article  Google Scholar 

  14. Wallraff, A. et al. Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics. Nature 431, 162–167 (2004)

    ADS  CAS  Article  Google Scholar 

  15. Bose, S., Jacobs, K. & Knight, P. L. Preparation of nonclassical states in cavities with a moving mirror. Phys. Rev. A 56, 4175–4186 (1997)

    ADS  CAS  Article  Google Scholar 

  16. Marshall, W., Simon, C., Penrose, R. & Bouwmeester, D. Towards quantum superpositions of a mirror. Phys. Rev. Lett. 91, 130401 (2003)

    ADS  MathSciNet  Article  Google Scholar 

  17. Vitali, D. et al. Optomechanical entanglement between a movable mirror and a cavity field. Phys. Rev. Lett. 98, 030405 (2007)

    ADS  CAS  Article  Google Scholar 

  18. Clerk, A. A., Marquardt, F. & Jacobs, K. Back-action evasion and squeezing of a mechanical resonator using a cavity detector. N. J. Phys. 10, 095010 (2008)

    Article  Google Scholar 

  19. Marquardt, F., Chen, J. P., Clerk, A. A. & Girvin, S. M. Quantum theory of cavity-assisted sideband cooling of mechanical motion. Phys. Rev. Lett. 99, 093902 (2007)

    ADS  Article  Google Scholar 

  20. Dobrindt, J. M., Wilson-Rae, I. & Kippenberg, T. J. Parametric normal-mode splitting in cavity optomechanics. Phys. Rev. Lett. 101, 263602 (2008)

    ADS  CAS  Article  Google Scholar 

  21. Hammerer, K., Aspelmeyer, M., Polzik, E. & Zoller, P. Establishing Einstein-Podolsky-Rosen channels between nanomechanics and atomic ensembles. Phys. Rev. Lett. 102, 020501 (2009)

    ADS  CAS  Article  Google Scholar 

  22. Wilson Rae, I., Nooshi, N., Dobrindt, J., Kippenberg, T. J. & Zwerger, W. Cavity-assisted backaction cooling of mechanical resonators. N. J. Phys. 10, 095007 (2008)

    Article  Google Scholar 

  23. Zhang, J., Peng, K. & Braunstein, S. L. Quantum-state transfer from light to macroscopic oscillators. Phys. Rev. A 68, 013808 (2003)

    ADS  Article  Google Scholar 

  24. Thompson, R. J., Rempe, G. & Kimble, H. J. Observation of normal-mode splitting for an atom in an optical cavity. Phys. Rev. Lett. 68, 1132–1135 (1992)

    ADS  CAS  Article  Google Scholar 

  25. Colombe, Y. et al. Strong atom–field coupling for Bose–Einstein condensates in an optical cavity on a chip. Nature 450, 272–276 (2007)

    ADS  CAS  Article  Google Scholar 

  26. Aoki, T. et al. Observation of strong coupling between one atom and a monolithic microresonator. Nature 443, 671–674 (2006)

    ADS  CAS  Article  Google Scholar 

  27. Reithmaier, J. P. et al. Strong coupling in a single quantum dot–semiconductor microcavity system. Nature 432, 197–200 (2004)

    ADS  CAS  Article  Google Scholar 

  28. Weisbuch, C., Nishioka, M., Ishikawa, A. & Arakawa, Y. Observation of the coupled exciton-photon mode splitting in a semiconductor quantum microcavity. Phys. Rev. Lett. 69, 3314–3317 (1992)

    ADS  CAS  Article  Google Scholar 

  29. Yoshie, T. et al. Vacuum Rabi splitting with a single quantum dot in a photonic crystal nanocavity. Nature 432, 200–203 (2004)

    ADS  CAS  Article  Google Scholar 

  30. Zhu, Y. et al. Vacuum Rabi splitting as a feature of linear-dispersion theory: analysis and experimental observations. Phys. Rev. Lett. 64, 2499–2502 (1990)

    ADS  CAS  Article  Google Scholar 

Download references


We are grateful to T. Corbitt, C. Genes, S. Goßler, P. K. Lam, G. Milburn, P. Rabl and P. Zoller for discussions. We also thank M. Metzler, R. Ilic and M. Skvarla (CNF), and K. C. Schwab and J. Hertzberg, for microfabrication support, and R. Blach for technical support. We acknowledge financial support from the Austrian Science Fund FWF, the European Commission and the Foundational Questions Institute. S.G. is a recipient of a DOC fellowship of the Austrian Academy of Sciences; S.G. and M.R.V. are members of the FWF doctoral programme Complex Quantum Systems (CoQuS).

Author Contributions All authors have made a significant contribution to the concept, design, execution or interpretation of the presented work.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Markus Aspelmeyer.

Supplementary information

Supplementary Information

This file contains Supplementary Data, Supplementary Figures S1-S3 with Legends and Supplementary References. (PDF 639 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gröblacher, S., Hammerer, K., Vanner, M. et al. Observation of strong coupling between a micromechanical resonator and an optical cavity field. Nature 460, 724–727 (2009).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


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.


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