Selective Efficient Quantum Process Tomography
  We present a new method for quantum process tomography. The method enables us to efficiently estimate, with fixed precision, any of the parameters characterizing a quantum channel. It is selective since one can choose to estimate the value of any specific set of matrix elements of the super-operator describing the channel. Also, we show how to efficiently estimate all the average survival probabilities associated with the channel (i.e., all the diagonal elements of its $\chi$--matrix. 
Ariel Bendersky, Fernando Pastawski and Juan Pablo Paz