  We present a tomographic protocol for the characterization of multiqubit
quantum channels. We discuss a specific class of input states, for which the
set of Pauli measurements at the output of the channel directly relates to its
Pauli transfer matrix components. We compare our results to those of standard
quantum process tomography, showing an exponential reduction in the number of
different experimental configurations required by a single matrix element
extraction, while keeping the same number of shots. This paves the way for more
efficient experimental implementations, whenever a selective knowledge of the
Pauli transfer matrix is needed. We provide several examples and simulations.
