We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T2 > 100 µs (T2 > 300 µs 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 ms. Our results violate a common viewpoint that the number of Josephson junctions in a superconducting circuit -over 10 2 here -must be minimized for best qubit coherence. We outline how the unique to fluxonium combination of long coherence time and large anharmonicity can benefit both gate-based and adiabatic quantum computing.

No abstract

No abstract

c = 1/3 (Z = 2.2 kΩ) [6]. Although the critical point is formulated in terms of the wave impedance of the collective mode, little is known even in theory about what happens to this mode upon crossing the phase transition. Traditional SI experiments focus on finding a universal scaling of (zero-frequency) arXiv:1805.07379v2 [cond-mat.supr-con]