Application of a Lyot filter plate in discrete frequency entanglement

Abstract

Non-degenerate frequency entanglement has been reported in several recent experiments, since its original observation with Spontaneous Parametric Down-conversion. We report on a configuration based on a Lyot plate, which overcomes shortcomings of prior work by avoiding post-selection and state projection losses. This makes the process suitable, in principle, for use in efficient QKD protocols based on photon pairs entangled in frequency at remote locations.