Simple representation of quantum process tomography

Abstract

We show that the Fano representation leads to a particularly simple and appealing form of the quantum process tomography matrix χF, in that the matrix χF 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. © 2009 The American Physical Society.