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Resolving the vacuum fluctuations of an optomechanical system using an artificial atom

Abstract

Heisenberg’s uncertainty principle results in one of the strangest quantum behaviours: a mechanical oscillator can never truly be at rest. Even at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations1,2. However, direct energy detection of the oscillator in its ground state makes it seem motionless1,3, and in linear position measurements detector noise can masquerade as mechanical fluctuations4,5,6,7. Thus, how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state8,9 and then amplify the remaining vacuum fluctuations into real energy quanta10. We monitor the photon/phonon-number distributions using a superconducting qubit11,12,13, allowing us to resolve the quantum vacuum fluctuations of the macroscopic oscillator’s motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.

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Figure 1: Device description and strong-coupling regime.
Figure 2: Cavity state preparation and readout.
Figure 3: Optomechanics with a number-resolving detector.

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Acknowledgements

We thank A. W. Sanders for taking the micrographs in Fig. 1b, c. This work was supported by the NIST Quantum Information Program.

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Contributions

F.L., J.D.T. and R.W.S. conceived and designed the experiment. F.L. fabricated the device and performed the measurement. F.L. and J.D.T. analysed the data. F.L., J.D.T. and R.W.S. wrote the manuscript. J.A. contributed to the fabrication process and provided experimental support.

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Correspondence to F. Lecocq.

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The authors declare no competing financial interests.

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Lecocq, F., Teufel, J., Aumentado, J. et al. Resolving the vacuum fluctuations of an optomechanical system using an artificial atom. Nature Phys 11, 635–639 (2015). https://doi.org/10.1038/nphys3365

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