Using Bifluxon Tunneling to Protect the Fluxonium Qubit

Summary

Demonstrates a partially protected fluxonium operated at zero external flux with a roughly $1\mu \text{H}$ superinductor. Resonant $4\pi$ phase slips couple wells differing by two fluxons while the qubit states retain different fluxon parity and nearly disjoint wavefunction support. The device achieved $T_1=177\pm 3\mu \text{s}$ and Hahn-echo $T_2^E=75\pm 5\mu \text{s}$ near a 3 GHz qubit frequency. This is a simpler, fluxonium-based bifluxon-tunnelling realization rather than the split-CPB Aharonov-Casher circuit demonstrated by Kalashnikov et al.

Cited In

• bifluxon-qubit