This project points to the experimental realization of suitably designed optical states for quantum communications uses. The quantum state will be conveniently manipulated by its projection on another one of predictable properties. The process will be realized by means of a conditional measurement performing a post-selection of the beam by monitoring a suitable observable on a fraction of it. The novel aspect of the proposed research relies on the application of this methods to multimode radiation, with the aim of providing tools to efficiently transmit information along more parallel quantum channels. Multimode quantum light will be produced by means of an optical parametric oscillator, operated in synchronously pumped configuration; this system has a huge potential for obtaining new quantum effects, and up to now, it has been very rarely used. The research will combine a theoretical description of the problem with its experimental realization. This project will complete and enlarge the range of the applicant’s competences. To this aim, it will benefit from the high level scientific quality of the host institution.