The flux qubit revisited to enhance coherence and reproducibility
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.; Yan, Fei; Gustavsson, Simon; Kamal, Archana; Orlando, Terry Philip; Oliver, William D; ... Show more Show less
MetadataShow full item record
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.
DepartmentMassachusetts 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
Nature Publishing Group
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.
Final published version