Experimental Realization of Optimal Noise Estimation for a General Pauli   Channel
  We present the experimental realization of the optimal estimation protocol for a Pauli noisy channel. The method is based on the generation of 2-qubit Bell states and the introduction of quantum noise in a controlled way on one of the state subsystems. The efficiency of the optimal estimation, achieved by a Bell measurement, is shown to outperform quantum process tomography. 
A.Chiuri, V. Rosati, G. Vallone, S. P\'adua, H. Imai, S. Giacomini, C.   Macchiavello, and P. Mataloni
quant-ph