High-Coherence Fluxonium Qubit

  title={High-Coherence Fluxonium Qubit},
  author={Long B. Nguyen and Yen-Hsiang Lin and Aaron Somoroff and Raymond A. Mencia and Nicholas Grabon and Vladimir E Manucharyan},
  journal={Physical Review X},
We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T2 > 100 microseconds (T2 > 300 microseconds in one device). Moreover, given the state of the art values of the surface loss tangent and the 1/f flux noise amplitude, coherence can be further improved beyond 1 millisecond. Our results violate a common viewpoint that the number of Josephson junctions in a superconducting circuit -- over 100 here -- must be minimized… 

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