Quantum estimation of states and operations for quantum technology

The emergent field of quantum technology holds promise of a twofold revolution in increasing precision of measurements and in the way information is processed, exchanged and stored. In particular, photonic states and devices are currently viewed as the most promising candidates to transport and manipulate quantum information, as optical radiation travels at maximum possible speed and it is almost unaffected by the interaction with the environment. In this context, a pillar for the implementation of quantum technology is a reliable set of diagnostics tools for the characterization of the information carriers, devices, and detectors. This talk is devoted to illustrate recent theoretical and experimental results for the estimation of quantum optical states and operations, including nonobservable quantities as entanglement, also enlighting the role of the italian community in the development of the field.