Fidelity of Single Qubit Maps
  We 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). 
M. D. Bowdrey, D. K. L. Oi, A. J. Short, K. Banaszek and J. A. Jones