W08.00013. Long Relaxation Times of a C-shunt Flux Qubit Coupled to a 3D Cavity

Presented by: Leonid Abdurakhimov


We present measurements of relaxation times of a capacitively shunted flux qubit embedded in a 3D microwave cavity. Qubit energy-relaxation times T1 were found to be in the range of 60-90 μs, and Hahn-echo coherence time T2E was about 80 μs. Using the CPMG dynamical decoupling sequence, the T1-limited coherence time T2CPMG of 160 μs was reached. Qubit energy relaxation could be attributed to quasiparticle tunneling, while dephasing times were limited by charge and critical-current noises at the optimal flux bias point and by 1/f flux noise elsewhere. With their relaxation times being comparable or exceeding previously reported values for other types of flux qubits, 3D c-shunt flux qubits can be utilized for quantum annealing, quantum magnetometry and spin sensing. *This work was partially supported by JST CREST (JPMJCR1774).


  • Leonid Abdurakhimov
  • Imran Mahboob
  • Hiraku Toida
  • Kousuke Kakuyanagi
  • Shiro Saito


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