Capacitively Shunted Flux Qubit with High Anharmonicity and Long Coherence Times

ORAL

Abstract

We present experiments on a three Josephson junction flux qubit with all junctions shunted by large capacitive pads. The qubit is capacitively coupled to a coplanar waveguide resonator for dispersive readout and capacitively coupled to a drive line for control. The qubit energy level structure has high anharmonicity, with the ratio of the second to the first transition frequency larger than 3. The dependence of the first two transition frequencies on flux is in excellent agreement with numerical simulations. Close to the symmetry point, the qubit has long relaxation time, in the tens of microseconds range. We characterize qubit dephasing using spin-echo and dynamical decoupling and we analyze the flux dependence of dephasing times to extract the flux noise power spectral density. In addition, we present measurement of multi-level coherence. Finally, we discuss the characterization of single-qubit gates using randomized benchmarking.

–

Presenters

  • Jiahao Shi

    Institute for Quantum Computing, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo

Authors

  • Jiahao Shi

    Institute for Quantum Computing, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo

  • Muhammet Ali Yurtalan

    Institute for Quantum Computing, Department of Electrical and Computer Engineering, and Waterloo Institute for Nanotechnology, University of Waterloo, Electrical and Computer Engineering, Institute for Quantum Computing, Waterloo Institute for Nanotechnology, University of Waterloo

  • Graydon JK Flatt

    Department of Physics & Astronomy, University of California, Los Angeles

  • Adrian Lupascu

    University of Waterloo, Institute for Quantum Computing, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo, Physics and Astronomy, Institute for Quantum Computing, Waterloo Institute for Nanotechnology, University of Waterloo