We present the first experimental realization of the quantum illumination protocol proposed by Lloyd [ Science 321 1463 (2008)] and S. Tan et al. [ Phys. Rev. Lett. 101 253601 (2008)], achieved in a simple feasible experimental scheme based on photon-number correlations. A main achievement of our result is the demonstration of a strong robustness of the quantum protocol to noise and losses that challenges some widespread wisdom about quantum technologies

We present a complete and exhaustive theory of signal-to-noiseratio in bipartite ghost imaging with classical (thermal) and quantum (twin beams) light. The theory is compared with experiment for both twin beams and thermal light in a certain regime of interest

In the last years the exploitation of specific properties of quantum states has disclosed the possibility of realising tasks beyond classical limits, creating the new field of quantum technologies [1,2,3,4,5,6,7,8,9]. Among them, quantum metrology and imaging aim to improve the sensitivity and/or resolution of measurements exploiting non-classical features such as squeezing and quantum correlations (entanglement and discordant states) [10,11,12,13,14]. Nevertheless, in most of the realistic scenarios losses and noise are known to nullify the advantage of adopting quantum strategies [15]. In this paper we describe in detail the first experimental realization of quantum illumination protocol aimed to target detection in a noisy environment, that preserves a strong advantage over the classical counterparts even in presence of large amount of noise and losses. The experiment, inspired by the theoretical ideas elaborated in [16,17,18,19] (see also [20,21]), has been performed exploiting only photon number correlations in twin beams. Thus, for its simplicity it can find widespread use. Even more important by challenging the common believe that real application of quantum technologies is limited by their fragility to noise and losses, it paves the way to their real application. arXiv:1307.3876v1 [quant-ph]