Nonlinear and Quantum Optical Properties and Applications of Intense Twin-Beams

In this review we present the main results of some experimental investigations that we performed in the last 10 years on optical twin-beam states. We explore twin-beam statistical properties and spatio-spectral coherence in different intensity regimes, from the mesoscopic to the macroscopic domain, also including pump depletion. We also characterize the quantum nature of the mesoscopic twin-beam states in terms of different nonclassicality criteria, all of them written for detected photons and demonstrate the generation of sub-Poissonian non-Gaussian states by conditional operations. Finally, we address a ghost-imaging protocol implemented with twin-beam states in the macroscopic regime.