  We report on design and fabrication of a new type of flux qubit that
capitalizes on intrinsic properties of submicron YBCO grain boundary junctions.
The operating point is protected from the fluctuations of the external fields,
already on the classical level; the effects of external perturbations are
absent, to the second or third order, depending on the character of the
coupling. We propose an experiment to observe quantum tunneling and Rabi
oscillations in the qubit. Estimate of the decoherence due to fluctuations of
the external flux is presented.
