Bifluxon: Fluxon-Parity-Protected Superconducting Qubit

Summary

Introduces and experimentally demonstrates the bifluxon qubit — a fluxon-parity-protected superconducting circuit consisting of a split Cooper-pair box shunted by a granular-aluminum superinductor. At odd island charge, Aharonov-Casher interference suppresses single-fluxon tunnelling and produces effective $4\pi$-periodic dynamics with logical wavefunctions in disjoint even- and odd-fluxon sectors. The prototype demonstrated a tenfold increase in $T_1$ (up to 100 μs) when protection was switched on; full dephasing protection remained a next-generation array goal.

Cited In

• bifluxon-qubit