Selective truncation of Fock-state expansion of an optical field can be achieved using projection synthesis. The process removes predetermined Fock states from the input field by conditional measurement and teleportation. We present a scheme based on multiport interferometry to perform projection synthesis. This scheme can be used both as a generalized quantum scissors device, which filters out Fock states with photon numbers higher than a predetermined value, and also as a quantum punching device, which selectively removes specific Fock states making holes in the Fock-state expansion of the input field.
@article{arxiv.quant-ph/0605146,
title = {Selective truncations of an optical state using projection synthesis},
author = {Adam Miranowicz and Sahin Kaya Ozdemir and Jiri Bajer and Masato Koashi and Nobuyuki Imoto},
journal= {arXiv preprint arXiv:quant-ph/0605146},
year = {2009}
}