The flux qubit revisited to enhance coherence and reproducibility
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The flux.pdf
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Author(s)
Birenbaum, Jeffrey
Sears, Adam P
Hover, David
Gudmundsen, Ted J.
Rosenberg, Danna
Samach, Gabriel
Weber, S
Yoder, Jonilyn L.
Clarke, John
Kerman, Andrew J.
Date Issued
November 2016
Journal
Nature Communications
Publisher
Nature Publishing Group
Citation
Yan, Fei; Gustavsson, Simon; Kamal, Archana; Birenbaum, Jeffrey; Sears, Adam P; Hover, David; Gudmundsen, Ted J. et al. “The Flux Qubit Revisited to Enhance Coherence and Reproducibility.” Nature Communications 7 (November 3, 2016): 12964. © 2016 Macmillan Publishers Limited, part of Springer Nature.
Version
Final published version
Abstract
The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point. Qubit relaxation times T₁ across 22 qubits are consistently matched with a single model involving resonator loss, ohmic charge noise and 1/f-flux noise, a noise source previously considered primarily in the context of dephasing. We furthermore demonstrate that qubit dephasing at the flux-insensitive point is dominated by residual thermal-photons in the readout resonator. The resulting photon shot noise is mitigated using a dynamical decoupling protocol, resulting in T₂≈85 μs, approximately the 2T₁ limit. In addition to realizing an improved flux qubit, our results uniquely identify photon shot noise as limiting T₂ in contemporary qubits based on transverse qubit–resonator interaction.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Research Laboratory of Electronics
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Creative Commons Attribution 4.0 International License
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DOI of Published Version
https://doi.org/10.1038/ncomms12964
