Letter | Published:

Nanomechanical motion measured with an imprecision below that at the standard quantum limit

Nature Nanotechnology volume 4, pages 820823 (2009) | Download Citation

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Abstract

Nanomechanical oscillators are at the heart of ultrasensitive detectors of force1, mass2 and motion3,4,5,6,7. As these detectors progress to even better sensitivity, they will encounter measurement limits imposed by the laws of quantum mechanics. If the imprecision of a measurement of the displacement of an oscillator8 is pushed below a scale set by the standard quantum limit, the measurement must perturb the motion of the oscillator by an amount larger than that scale. Here we show a displacement measurement with an imprecision below the standard quantum limit scale. We achieve this imprecision by measuring the motion of a nanomechanical oscillator with a nearly shot-noise limited microwave interferometer9. As the interferometer is naturally operated at cryogenic temperatures, the thermal motion of the oscillator is minimized, yielding an excellent force detector with a sensitivity of 0.51 aN Hz−1/2. This measurement is a critical step towards observing quantum behaviour in a mechanical object.

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Acknowledgements

We acknowledge support from the National Science Foundation's Physics Frontier Center for Atomic, Molecular and Optical Physics and from the National Institute of Standards and Technology. T. D. acknowledges support from the Deutsche Forschungsgemeinschaft (DFG). We thank N. E. Flowers-Jacobs for valuable conversations and technical assistance, and K. D. Irwin, G. C. Hilton, and L. R. Vale for fabrication, and help with the design, of the JPA.

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Affiliations

  1. JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309, USA

    • J. D. Teufel
    • , T. Donner
    • , M. A. Castellanos-Beltran
    • , J. W. Harlow
    •  & K. W. Lehnert
  2. Department of Physics, University of Colorado, Boulder, Colorado 80309, USA

    • M. A. Castellanos-Beltran
    • , J. W. Harlow
    •  & K. W. Lehnert

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Contributions

All authors contributed to project planning and data analysis. Experimental work was carried out by J.D.T., T.D., M.A.C. and J.W.H. Samples were fabricated by J.W.H. The manuscript was written by J.D.T., T.D., J.W.H. and K.W.L.

Corresponding author

Correspondence to K. W. Lehnert.

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DOI

https://doi.org/10.1038/nnano.2009.343

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