High-Coherence Fluxonium Qubit

• Main Authors: Long B. Nguyen, Yen-Hsiang Lin, Aaron Somoroff, Raymond Mencia, Nicholas Grabon, Vladimir E. Manucharyan
• Format: Article
• Language: English
• Published: American Physical Society 2019-11-01
• Series: Physical Review X
• Online Access: http://doi.org/10.1103/PhysRevX.9.041041

We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T_{2}>100  μs (T_{2}>400  μs in one device). Moreover, given the state-of-the-art values of the surface loss tangent and the 1/f flux-noise amplitude, the coherence time 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.