Integer Fluxonium Qubit
Raymond Mencia, Wei-Ju Lin, Hyunheung Cho, Maxim Vavilov, Vladimir Manucharyan · PRX Quantum · 2024
We describe a superconducting qubit derived from operating a properly designed fluxonium circuit in a zero magnetic field. The qubit has a frequency of about 4 GHz and an energy relaxation quality factor Q ≈ 0.7 × 10 7 , even though the dielectric loss quality factor of the circuit components is in the low- 10 5 range. The Ramsey coherence time exceeds 100 μ s , and the average fidelity of Clifford gates is benchmarked to F > 0.999 . These figures are expected to improve with optimized fabrication and measurement procedures. Our work establishes a ready-to-use “partially protected” superconducting qubit functioning in the frequency range of conventional transmons. Published by the American Physical Society 2024