2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89989We describe a simple way of characterizing the average fidelity between a unitary (or anti-unitary) operator and a general operation on a single qubit, which only involves calculating the fidelities for a few pure input states, and discuss possible applications to experimental techniques including Nuclear Magnetic Resonance (NMR).5 pages RevTex4, no figures. Physics Letters A in press. Supersedes quant-ph/0103090 and quant-ph/0103060Quantum Physicstext