The flux qubit revisited to enhance coherence and reproducibility

• DOI: 10.1038/ncomms12964
• Publication Date: 2016-11-03T09:40:39Z
• Authors: Fei Yan; Simon Gustavsson; Archana Kamal; Jeffrey Birenbaum; Adam P Sears; David Hover; Ted J. Gudmundsen; Danna Rosenberg; Gabriel Samach; S Weber; Jonilyn L. Yoder; Terry P. Orlando; John Clarke; Andrew J. Kerman; William D. Oliver
• Keywords: Flux qubit; Dephasing; Charge qubit; Dynamical decoupling

The scalable application of quantum information science will stand on reproducible and controllable high-coherence bits (qubits). Here, we revisit the design fabrication superconducting flux qubit, achieving a planar device with broad frequency tunability, strong anharmonicity, high reproducibility, relaxation times in excess $40\,\mu$s at its flux-insensitive point. Qubit $T_1$ across 22 qubits are consistently matched single model involving resonator loss, ohmic charge noise, 1/f noise source previously considered primarily context dephasing. We furthermore demonstrate that qubit dephasing point is dominated by residual thermal photons readout resonator. resulting photon shot mitigated using dynamical decoupling protocol, $T_2\approx 85\,\mu$s, approximately $2T_1$ limit. In addition to realizing an improved our results uniquely identify as limiting $T_2$ contemporary based transverse qubit-resonator interaction.