Proposal for generating a two-photon added coherent state via down-conversion with a single crystal

Zavatta et al. [A. Zavatta, S. Viciani, M. Bellini, Science 306 (2004) 660; A. Zavatta, S. Viciani, M. Bellini, Phys. Rev. A 72 (2006) 023820], using parametric down-conversion, have carried out experiments to conditionally generate a single-photon added coherent state. In this Letter, we propose an extension of their method in order to generate the two-photon added coherent state, and point the way toward generating m-photon added coherent states for m>2, all using only one down-conversion crystal.