Resolved-sideband and cryogenic cooling of an optomechanical resonator

Article metrics


Cooling a mechanical oscillator to its quantum ground state enables the exploration of the quantum nature and the quantum–classical boundary of an otherwise classical system1,2,3,4,5,6,7. In analogy to laser cooling of trapped ions8, ground-state cooling of an optomechanical system can in principle be achieved by radiation-pressure cooling in the resolved-sideband limit where the cavity photon lifetime far exceeds the mechanical oscillation period9,10,11. Here, we report the experimental demonstration of an optomechanical system that combines both resolved-sideband and cryogenic cooling. Mechanical oscillations of a deformed silica microsphere are coupled to optical whispering-gallery modes that can be excited through free-space evanescent coupling12,13. By precooling the system to 1.4 K, a final average phonon occupation as low as 37 quanta, limited by ultrasonic attenuation in silica, is achieved. With diminishing ultrasonic attenuation, we anticipate that the ground-state cooling can be achieved when the resonator is precooled to a few hundred millikelvin in a 3He cryostat.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Free-space coupling of WGMs.
Figure 2: Mechanical modes and cryogenic cooling.
Figure 3: Resolved-sideband cooling in a cryogenic environment.
Figure 4: Average phonon occupation.


  1. 1

    Schwab, K. C. & Roukes, M. L. Putting mechanics into quantum mechanics. Phys. Today 58, 36–42 (2005).

  2. 2

    Braginsky, V. B. & Khalili, F. Y. Quantum Measurement (Cambridge Univ. Press, 1992).

  3. 3

    Fabre, C., Pinard, M., Bourzeix, S., Heidmann, A., Giacobino, E. & Reynaud, S. Quantum-noise reduction using a cavity with a movable mirror. Phys. Rev. A. 49, 1337–1343 (1994).

  4. 4

    Bose, S., Jacobs, K. & Knight, P. L. Scheme to probe the decoherence of a macroscopic object. Phys. Rev. A. 59, 3204–3210 (1999).

  5. 5

    Mancini, S., Giovannetti, V., Vitali, D. & Tombesi, P. Entangling macroscopic oscillators exploiting radiation pressure. Phys. Rev. Lett. 88, 120401 (2002).

  6. 6

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

  7. 7

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

  8. 8

    Diedrich, F., Bergquist, J. C., Itano, W. M. & Wineland, D. J. Laser cooling to the zero-point energy of motion. Phys. Rev. Lett. 62, 403–406 (1989).

  9. 9

    Wilson-Rae, I., Nooshi, N., Zwerger, W. & Kippenberg, T. J. Theory of ground state cooling of a mechanical oscillator using dynamical backaction. Phys. Rev. Lett. 99, 093901 (2007).

  10. 10

    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).

  11. 11

    Schliesser, A., Riviere, R., Anetsberger, G., Arcizet, O. & Kippenberg, T. J. Resolved-sideband cooling of a micromechanical oscillator. Nature Phys. 4, 415–419 (2008).

  12. 12

    Lacey, S., Wang, H., Foster, D. H. & Nockel, J. U. Directional tunneling escape from nearly spherical optical resonators. Phys. Rev. Lett. 91, 033902 (2003).

  13. 13

    Park, Y.-S., Cook, A. K. & Wang, H. Cavity QED with diamond nanocrystals and silica microspheres. Nano. Lett. 6, 2075–2079 (2006).

  14. 14

    Braginsky, V. B. Measurement of Weak Forces in Physics Experiments (Univ. Chicago Press, 1977).

  15. 15

    Kippenberg, T. J. & Vahala, K. J. Cavity optomechanics: Back-action at the mesoscale. Science 321, 1172–1176 (2008).

  16. 16

    Arcizet, O., Cohadon, P.-F., Briant, T., Pinard, M. & Heidmann, A. Radiation-pressure cooling and optomechanical instability of a micromirror. Nature 444, 71–74 (2006).

  17. 17

    Gigan, S. et al. Self-cooling of a micromirror by radiation pressure. Nature 444, 67–70 (2006).

  18. 18

    Schliesser, A., Del’Haye, P., Nooshi, N., Vahala, K. J. & Kippenberg, T. J. Radiation pressure cooling of a micromechanical oscillator using dynamical backaction. Phys. Rev. Lett. 97, 243905 (2006).

  19. 19

    Ma, R. et al. Radiation-pressure-driven vibrational modes in ultrahigh-Q silica microspheres. Opt. Lett. 32, 2200–2202 (2007).

  20. 20

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

  21. 21

    Cohadon, P. F., Heidmann, A. & Pinard, M. Cooling of a mirror by radiation pressure. Phys. Rev. Lett. 83, 3174–3177 (1999).

  22. 22

    Kleckner, D. & Bouwmeester, D. Sub-kelvin optical cooling of a micromechanical resonator. Nature 444, 75–78 (2006).

  23. 23

    Groblacher, S., Gigan, S., Bohm, H. R., Zeilinger, A. & Aspelmeyer, M. Radiation-pressure self-cooling of a micromirror in a cryogenic environment. Europhys. Lett. 81, 54003 (2008).

  24. 24

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

  25. 25

    Teufel, J. D., Harlow, J. W., Regal, C. A. & Lehnert, K. W. Dynamical backaction of microwave fields on a nanomechanical oscillator. Phys. Rev. Lett. 101, 197203 (2008).

  26. 26

    Braginsky, V. B., Gorodetsky, M. L. & Ilchenko, V. S. Quality-factor and nonlinear properties of optical whispering-gallery modes. Phys. Lett. A 137, 393–397 (1989).

  27. 27

    Vahala, K. J. Optical microcavities. Nature 424, 839–846 (2003).

  28. 28

    Arcizet, O. et al. High-sensitivity optical monitoring of a micromechanical resonator with a quantum-limited optomechanical sensor. Phys. Rev. Lett. 97, 133601 (2006).

  29. 29

    Vacher, R., Courtens, E. & Foret, M. Anharmonic versus relaxational sound damping in glasses. 2. Vitreous silica. Phys. Rev. B 72, 214205 (2005).

  30. 30

    Pohl, R. O., Liu, X. & Thompson, E. Low-temperature thermal conductivity and acoustic attenuation in amorphous solids. Rev. Mod. Phys. 74, 991–1013 (2002).

  31. 31

    Park, Y.-S. & Wang, H. Regenerative pulsation in silica microspheres. Opt. Lett. 32, 3104–3106 (2007).

Download references


This work is supported by NSF and ARL-ONAMI.

Author information

Y.-S.P. and H.W. conceived the experiment, analysed the experimental result and prepared the manuscript. Y.-S.P. carried out the experiment.

Correspondence to Hailin Wang.

Supplementary information

Supplementary Information

Supplementary Information (PDF 529 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading