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Harnessing electro-optic correlations in an efficient mechanical converter

Nature Physicsvolume 14pages10381042 (2018) | Download Citation


An optical network of superconducting quantum bits (qubits) is an appealing platform for quantum communication and distributed quantum computing, but developing a quantum-compatible link between the microwave and optical domains remains an outstanding challenge. Operating at T < 100 mK temperatures, as required for quantum electrical circuits, we demonstrate a mechanically mediated microwave–optical converter with 47% conversion efficiency, and use a classical feed-forward protocol to reduce added noise to 38 photons. The feed-forward protocol harnesses our discovery that noise emitted from the two converter output ports is strongly correlated because both outputs record thermal motion of the same mechanical mode. We also discuss a quantum feed-forward protocol that, given high system efficiencies, would allow quantum information to be transferred even when thermal phonons enter the mechanical element faster than the electro-optic conversion rate.

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We thank J. Thompson and M. Holland for fruitful conversations and K. Cicak for assistance with device fabrication. We acknowledge funding from AFOSR MURI grant number FA9550-15-1-0015, the NSF under grant number PHYS 1734006, DURIP and AFOSR PECASE.

Author information

Author notes

  1. These authors contributed equally: A. P. Higginbotham, P. S. Burns, M. D. Urmey.


  1. JILA, University of Colorado and NIST, Boulder, CO, USA

    • A. P. Higginbotham
    • , P. S. Burns
    • , M. D. Urmey
    • , R. W. Peterson
    • , N. S. Kampel
    • , B. M. Brubaker
    • , G. Smith
    • , K. W. Lehnert
    •  & C. A. Regal
  2. Department of Physics, University of Colorado, Boulder, CO, USA

    • A. P. Higginbotham
    • , P. S. Burns
    • , M. D. Urmey
    • , R. W. Peterson
    • , N. S. Kampel
    • , B. M. Brubaker
    • , G. Smith
    • , K. W. Lehnert
    •  & C. A. Regal
  3. National Institute of Standards and Technology (NIST), Boulder, CO, USA

    • A. P. Higginbotham
    • , B. M. Brubaker
    •  & K. W. Lehnert
  4. Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA

    • G. Smith


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A.P.H., P.S.B. and M.D.U. conducted the experiment and analysed data. A.P.H, P.S.B., M.D.U., R.W.P. and N.S.K. designed and constructed the measurement network. M.D.U. and R.W.P. designed and constructed the optical cavity. P.S.B. designed and fabricated the flip-chip device. A.P.H. and G.S. developed feed-forward theory. A.P.H., P.S.B., M.D.U., B.M.B., G.S., K.W.L. and C.A.R. wrote the manuscript. C.A.R. and K.W.L. supervised the work. All authors commented on the results and manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to P. S. Burns.

Supplementary information

  1. Supplementary Information

    Supplementary Notes 1–7, Supplementary Table 1, Supplementary Figures 1–6, Supplementary References 1–10

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