Manipulations of chaotic and ghost images for non-local information retrieval

We present experiments of chi((2)) difference-frequency processes at frequency degeneracy in regime of high intensity. In the first experiment, we exploit ghost-imaging in the context of quantum cryptography in an attempt to overcome the limitation of the quantum key distribution of keys as long as the image The code to be encrypted is the string of the power values measured by Alice in the test arm. In the second experiment, we generate frequency down-converted images that are chaotic as, at each laser shot, both the field at 2 omega illuminating the object to be imaged and the seed-field at omega are made pseudo-thermal in space. The images are recovered from the recorded chaotic ones by correlating the local intensity fluctuations with those of the seed-field Fourier components. Calculating the correlations in parallel with many Fourier components allows image retrieval by averaging on ensembles of fewer recorded images.