The generation of Fock-states in the one-atom maser

In recent experiments it was demonstrated that number or Fock states of the field of the one-atom maser can be generated. Two types of experiment have been performed. In the first one, the Fock states are achieved in steady s tate via the so-called trapping states of the micromaser field. In the seco nd experiment the number states were generated in a dynamical experiment by state reduction. In the latter case the generated field was afterwards pro bed by observing the dynamics of a probe atom in the held. Finally the gene ration of GHZ states in the micromaser is discussed using the trapping stat es in the cavity.