  We show that the Fano representation leads to a particularly simple and
appealing form of the quantum process tomography matrix $\chi_{_F}$, in that
the matrix $\chi_{_F}$ is real, the number of matrix elements is exactly equal
to the number of free parameters required for the complete characterization of
a quantum operation, and these matrix elements are directly related to
evolution of the expectation values of the system's polarization measurements.
These facts are illustrated in the examples of one- and two-qubit quantum noise
channels.
