Generation of nonclassical states of light via truncation of mixed states

A possible way of generating nonclassical states of light is via the truncation of a given state in the Fock basis. In recent work, we presented an alternative scheme for such quantum scissors [Phys. Rev. A 104, 033715 (2021)], employing a nondegenerate parametric amplifier, a beam splitter, and photodetectors. An advantage of this setup is that it does not require the generation of Fock states beforehand, as in previous proposals. Here we extend this treatment to mixed input states. We show the possibilities of generating truncated states with either a maximum Fock number N or states having a minimum Fock number N. We discuss two specific examples of states to be truncated: (i) the thermal state and (ii) the phase-diffused coherent state. In either case, the generated field states can present sub-Poissonian statistics as well as non-Gaussian character. These nonclassical properties can be adjusted by changing the parameters of the scissors, e.g., the amplifier strength and the beam-splitter transmittance. (C) 2022 Optics Publishing Group