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Sub-kelvin optical cooling of a micromechanical resonator


Micromechanical resonators, when cooled down to near their ground state, can be used to explore quantum effects such as superposition and entanglement at a macroscopic scale1,2,3. Previously, it has been proposed to use electronic feedback to cool a high frequency (10 MHz) resonator to near its ground state4. In other work, a low frequency resonator was cooled from room temperature to 18 K by passive optical feedback5. Additionally, active optical feedback of atomic force microscope cantilevers has been used to modify their response characteristics6, and cooling to approximately 2 K has been measured7. Here we demonstrate active optical feedback cooling to 135 ± 15 mK of a micromechanical resonator integrated with a high-quality optical resonator. Additionally, we show that the scheme should be applicable at cryogenic base temperatures, allowing cooling to near the ground state that is required for quantum experiments—near 100 nK for a kHz oscillator.

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  1. 1

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

  2. 2

    Mancini, S., Vitali, D., Giovannetti, V. & Tombesi, P. Stationary entanglement between macroscopic mechanical oscillators. Eur. Phys. J. D 22, 417–422 (2003)

  3. 3

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

  4. 4

    Hopkins, A., Jacobs, K., Habib, S. & Schwab, K. Feedback cooling of a nanomechanical resonator. Phys. Rev. B 68, 235238 (2003)

  5. 5

    Metzger, C. H. & Karrai, K. Cavity cooling of a microlever. Nature 432, 1002–1005 (2004)

  6. 6

    Mertz, J., Marti, O. & Mlynek, K. Regulation of a microcantilever response by force feedback. Appl. Phys. Lett. 62, 2344–2346 (1993)

  7. 7

    Bruland, K. J., Garbini, J. L., Dougherty, W. M. & Sidles, J. A. Optimal control of force microscope cantilevers. II. Magnetic coupling implementation. J. Appl. Phys. 80, 1959–1964 (1996)

  8. 8

    Kleckner, D. et al. High finesse opto-mechanical cavity with a movable thirty-micron-size mirror. Phys. Rev. Lett. 96, 173901 (2006)

  9. 9

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

  10. 10

    Turner, L. D., Weber, W. P., Hawthorn, C. J. & Scholten, R. E. Frequency noise characterisation of narrow linewidth diode lasers. Opt. Commun. 201, 391–397 (2002)

  11. 11

    Vitali, B. D., Mancini, S., Ribichini, L. & Tombesi, P. Mirror quiescence and high-sensitivity position measurements with feedback. Phys. Rev. A 65, 063803 (2002)

  12. 12

    Joos, E. et al. Decoherence and the Appearance of a Classical World in Quantum Theory 2nd edn (Springer, New York, 2003)

  13. 13

    Zurek, W. H. Decoherence and the transition from quantum to classical. Phys. Today 44, 36–44 (1991)

  14. 14

    Parpia, J. M. et al. Optimization procedure for the cooling of liquid 3He by adiabatic demagnetization of praseodymium nickel. Rev. Sci. Instrum. 56, 437–443 (1985)

  15. 15

    Moussy, N., Courtois, A. & Pannetier, B. A very low temperature scanning tunnelling microscope for the local spectroscopy of mesoscopic structures. Rev. Sci. Instrum. 71, 128–131 (2001)

  16. 16

    Mamin, H. J. & Rugar, D. Sub-attonewton force detection at millikelvin temperatures. Appl. Phys. Lett. 79, 3358–3360 (2001)

  17. 17

    Courty, J. M., Heidman, A. & Pinard, M. Quantum limits of cold damping with optomechanical coupling. Eur. Phys. J. D 17, 399–408 (2001)

  18. 18

    Schwab, K., Henriksen, E. A., Worlock, J. M. & Roukes, M. L. Measurement of the quantum of thermal conductance. Nature 404, 974–977 (2000)

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This work was supported by the National Science Foundation. We thank M. de Dood, H. Eisenberg, S. Hastings, W. Irvine, A. Kahl, G. Khoury, W. Marshall and C. Simon for their contributions at earlier stages of this work.

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Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Correspondence to Dustin Kleckner.

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Figure 1: The experimental system.
Figure 2: Single-sided thermal vibration spectrum of the cantilever as it is cooled.
Figure 3: Temporal response of the cantilever to cooling pulses.
Figure 4: Response of the cantilever to an external intensity-modulated laser.


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