Kousuke Kakuyanagi

A long-lived capacitively shunted flux qubit embedded in a 3D cavity

  1. Leonid V. Abdurakhimov,
  2. Imran Mahboob,
  3. Hiraku Toida,
  4. Kousuke Kakuyanagi,
  5. and Shiro Saito
We report the experimental realization of a 3D capacitively-shunt superconducting flux qubit with long coherence times. At the optimal flux bias point, the qubit demonstrates energy
relaxation times in the 60-90 μs range, and Hahn-echo coherence time of about 80 μs which can be further improved by dynamical decoupling. Qubit energy relaxation can be attributed to quasiparticle tunneling, while qubit dephasing is caused by flux noise away from the optimal point. Our results show that 3D c-shunt flux qubits demonstrate improved performance over other types of flux qubits which is advantageous for applications such as quantum magnetometry and spin sensing.
arxiv pdf