  We propose a protected qubit which is `dual' to a suggestion of a
superconducting current mirror qubit [A. Kitaev, arXiv:0609441 (2006)]. Our
construction can be regarded as the magnetic analogue of Kitaev's proposal: it
inherits the intrinsic fault-tolerance of the current mirror qubit, but may
perform better than it in the laboratory, since magnetic noise is generally
less of a problem than electric noise. We adapt the scheme for universal
fault-tolerant quantum computation proposed by Kitaev to our construction.
