  A generalized Mach-Zehnder-type interferometer equipped with cross-Kerr
elements is proposed to convert N-photon truncated single-mode quantum states
into (N+1)-mode single-photon states, which are suitable for further state
manipulation by means of beam splitter arrays and ON/OFF-detections, and vice
versa. Applications to the realization of unitary and non-unitary
transformations, quantum state reconstruction, and quantum telemanipulation are
studied.
