[EN] Quantum Illumination is a novel technique which exploits quantum entanglement as a resource to detect the presence of an object with higher accuracy or smaller number of photons. The applications go from detection of trapped molecules to quantum radars, detection of cloaked objets and better weather forecasts. Here we will present Gaussian states, a paradigmatic family of quantum states in quantum optics. We will study the best classical and quantum Gaussian illumination protocols and compare them. Finally, we will introduce the photon subtraction operation, which de-Gaussianizes quantum states, and compare the performance of the new non-Gaussian protocol with the aforementioned ones.