Amplification of optical Schrödinger cat states with an implementation protocol based on a frequency comb

Abstract

We proposed and analyzed a scheme to generate large-size Schrödinger cat states based on linear operations of Fock states, squeezed vacuum states, and conditional measurements. By conducting conditional measurements via photon number detectors, two unbalanced small-amplitude Schrödinger kitten states combined by a beam splitter can be amplified to a large-size cat state with the same parity. According to simulation results, two Schrödinger odd kitten states with amplitudes of |β|=1.06 and |β|=1.11 generated from one-photon-subtracted 3 dB squeezed vacuum states, are amplified to an odd cat state of |β|=1.73 with a fidelity of F=99%. A large-size Schrödinger odd cat state with |β|=2.51 and F=97.30% is predicted when 5.91 dB squeezed vacuum states are employed. According to the analysis on the impacts of experimental imperfections in practice, Schrödinger odd cat states of |β|>2 are available. A feasible configuration based on a quantum frequency comb is developed to realize the large-size cat state generation scheme we proposed.