Conditional generation of arbitrary single-mode quantum states of light   by repeated photon subtractions
  We propose a scheme for the conditional generation of arbitrary finite superpositions of (squeezed) Fock states in a single mode of a traveling optical field. The suggested setup requires only a source of squeezed states, beam splitters, strong coherent beams, and photodetectors with single-photon sensitivity. The method does not require photodetectors with a high efficiency nor with a single-photon resolution. 
Jaromir Fiurasek, Raul Garcia-Patron, Nicolas J. Cerf