Nonlinear Coherent Loss

Abstract

We discuss exploiting artificially designed nonlinear coherent loss for generating non-classical states of a bosonic mode. Of special interest is the case when superpositions of Fock states are generated. We discuss conditions necessary for generation of pure superpositions and estimate maximal achievable fidelity. It is shown that the fidelity can be arbitrary close to unity for generation of either single Fock state, or infinite superposition of equidistant Fock states (e.g. a superposition of Fock states with odd number of particles), but is limited by the value 0.94, for instance, for superpositions of any two Fock states. Certain general necessary and (or) sufficient conditions for generation of pure states are also provided and illustrated by examples.