Generation and detection of Fock states of the radiation field

Recent widely discussed applications in quantum information and quantum cryptography require radiation sources able to produce a fixed number of photons. In this paper we review the work performed in our laboratory to produce such fields on demand. Two different methods are described. The first one is based on the micromaser operating under the conditions of a trapping state. The second device uses a single ion in an optical cavity. The latter setup was recently realized in our laboratory.