Abstract

The motion of micrometre-sized mechanical resonators can now be controlled and measured at the fundamental limits imposed by quantum mechanics. These resonators have been prepared in their motional ground state1,2,3 or in squeezed states4,5,6, measured with quantum-limited precision7, and even entangled with microwave fields8. Such advances make it possible to process quantum information using the motion of a macroscopic object. In particular, recent experiments have combined mechanical resonators with superconducting quantum circuits to frequency-convert, store and amplify propagating microwave fields9,10,11,12. But these systems have not been used to manipulate states that encode quantum bits (qubits), which are required for quantum communication and modular quantum computation13,14. Here we demonstrate the conversion of propagating qubits encoded as superpositions of zero and one photons to the motion of a micromechanical resonator with a fidelity in excess of the classical bound. This ability is necessary for mechanical resonators to convert quantum information between the microwave and optical domains15,16,17 or to act as storage elements in a modular quantum information processor12,13,18. Additionally, these results are an important step towards testing speculative notions that quantum theory may not be valid for sufficiently massive systems19.

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Acknowledgements

We acknowledge advice from C. Axline, M. Castellanos-Beltran, L. Frunzio, S. Glancy, W. F. Kindel and F. Lecocq as well as technical assistance from R. Delaney and H. Greene. We thank P. Blanchard for assistance in taking the micrograph shown in Fig. 1b. We acknowledge funding from the National Science Foundation (NSF) under grant number 1125844, AFOSR MURI under grant number FA9550-15-1-0015, and the Gordon and Betty Moore Foundation. A.P.R. acknowledges support from the NSF Graduate Research Fellowship under grant number DGE 1144083. L.D.B. acknowledges the support of the ARO QuaCGR Fellowship.

Author information

Affiliations

  1. JILA, Boulder, Colorado 80309-0440, USA

    • A. P. Reed
    • , L. Sletten
    • , X. Ma
    •  & K. W. Lehnert
  2. Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA

    • A. P. Reed
    • , K. H. Mayer
    • , L. Sletten
    • , X. Ma
    •  & K. W. Lehnert
  3. National Institute of Standards and Technology (NIST), Boulder, Colorado 80305, USA

    • K. H. Mayer
    • , J. D. Teufel
    • , E. Knill
    •  & K. W. Lehnert
  4. Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA

    • L. D. Burkhart
    • , W. Pfaff
    • , M. Reagor
    •  & R. J. Schoelkopf
  5. Rigetti Computing, 775 Heinz Avenue, Berkeley, California 94710, USA

    • M. Reagor
  6. Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA

    • E. Knill

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Contributions

A.P.R. and K.W.L. designed the experiment. A.P.R. performed the measurements. K.H.M. designed the tomographic analysis. A.P.R., K.H.M., J.D.T., E.K. and K.W.L. analysed the results. A.P.R., K.H.M., J.D.T. and K.W.L. wrote the manuscript. L.D.B. and A.P.R. fabricated the devices. A.P.R., L.D.B., W.P., M.R., L.S., X.M. and R.J.S. designed and constructed the photon source.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to A. P. Reed.

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DOI

https://doi.org/10.1038/nphys4251

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