  We describe a superconducting qubit derived from operating a properly
designed fluxonium circuit in a zero magnetic field. The qubit has a frequency
of about 4 GHz and the energy relaxation quality factor $Q \approx 0.7\times
10^7$, even though the dielectric loss quality factor of the circuit components
is in the low $10^5$ range. The Ramsey coherence time exceeds 100 us, and the
average fidelity of Clifford gates is benchmarked to $\mathcal{F} > 0.999$.
These figures are likely to improve by an order of magnitude with optimized
fabrication and measurement procedures. Our work establishes a ready-to-use
``partially protected" superconducting qubit with an error rate comparable to
the best transmons.
