Quantum process matrices as images: new tools to design novel denoising methods

Inferring a process matrix characterizing a quantum channel from experimental measure- ments is a key issue of quantum information. Sometimes the noise affecting the measured counts brings to matrices very different from the expected ones and the mainly used es- timation procedure, i.e. the maximum likelihood estimation (MLE), is also characterized by several drawbacks. To lower the noise could be necessary to increase the experimental resources, e.g. time for each measurement. In this paper, an alternative procedure, based on suitable Neural Networks, has been implemented and optimized to obtain a denoised process matrix and this approach has been tested with a specific quantum channel, i.e. a Control Phase. This promising method relies on the analogy that can be established between the elements of a process matrix and the pixels of an im