The flux qubit revisited to enhance coherence and reproducibility

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 T 1 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…

• NS
  National Science Foundation

  Awards: FA8721-05-C-0002, PHY-1415514, 1415514
• OO
  Office of the Director of National Intelligence
• IA
  Intelligence Advanced Research Projects Activity

  Award: FA8721-05-C-0002
• NO
  NIH Office of the Director
• AR
  Army Research Office

  Awards: W911NF-14-1, W911NF, W911NF-14-1-0682