Article

Cooling-by-measurement and mechanical state tomography via pulsed optomechanics

  • Nature Communications 4, Article number: 2295 (2013)
  • doi:10.1038/ncomms3295
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Abstract

Observing a physical quantity without disturbing it is a key capability for the control of individual quantum systems. Such back-action-evading or quantum non-demolition measurements were first introduced in the 1970s for gravitational wave detection, and now such techniques are an indispensable tool throughout quantum science. Here we perform measurements of the position of a mechanical oscillator using pulses of light with a duration much shorter than a period of mechanical motion. Utilizing this back-action-evading interaction, we demonstrate state preparation and full state tomography of the mechanical motional state. We have reconstructed states with a position uncertainty reduced to 19 pm, limited by the quantum fluctuations of the optical pulse, and we have performed ‘cooling-by-measurement’ to reduce the mechanical mode temperature from an initial 1,100 to 16 K. Future improvements to this technique will allow for quantum squeezing of mechanical motion, even from room temperature, and reconstruction of non-classical states exhibiting negative phase-space quasi-probability.

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Acknowledgements

We thank K. Hammerer, S. G. Hofer, M. S. Kim, G. J. Milburn, I. Pikovski, R. Riedinger and J. Schmöle for useful discussion. M.R.V. is a member of the FWF Doctoral Programme CoQuS (W 1210) and is a recipient of a DOC fellowship of the Austrian Academy of Sciences. Microfabrication was carried out at the Zentrum für Mikro- und Nanostrukturen (ZMNS) of the Technische Universität Wien and the epitaxial multilayer was grown by Markus Weyers’ group at the The Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH), Berlin (Germany). We thank the European Commission (QESSENCE, CQOM), the European Research Council (ERC QOM), the Vienna Science and Technology Fund (WWTF) and the Austrian Science Fund (FWF) (START, SFB FOQUS) for their support.

Author information

Affiliations

  1. University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), Boltzmanngasse 5 A-1090, Vienna, Austria

    • M. R. Vanner
    • , J. Hofer
    • , G. D. Cole
    •  & M. Aspelmeyer

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Contributions

All authors contributed to the experiment, the data analysis and writing of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to M. R. Vanner.

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