Squeezed Fock state by inconclusive photon subtraction

Abstract

We analyse in detail the properties of the conditional state recently obtained by Wenger et al (2004 Phys. Rev. Lett. 92 153601) by means of inconclusive photon subtraction (IPS) from a squeezed vacuum state . The IPS process can be characterized by two parameters: the IPS transmissivity τ and the photodetection quantum efficiency η. We found that the conditional state approaches the squeezed Fock state when , i.e., in the limit of single-photon subtraction. For nonunit IPS transmissivity and nonunit quantum efficiency, the conditional state remains close to the target state, i.e., shows a high fidelity, as long as the squeezing parameter is not too large. The purity and the nonclassicality of the conditional state are also investigated and a nonclassicality threshold on the IPS parameters is derived.