Multiphoton path-entanglement generation by concurrent parametric down-conversion in a single χ(2) nonlinear photonic crystal

摘要

We propose a two-dimensional χ(2) nonlinear photonic crystal capable of satisfying quasi-phase-matchingnconditions for two or three parametric down-conversions simultaneously. Seeded by a two-mode coherent state,nthis crystal can produce two-, three-, four-, or five-photon path-entangled states, provided the correspondingnnumber photons are produced, i.e., in a postselection-free way. In particular, up to five-photon NOON state cannbe generated, which enables phase supersensitive measurements at the Heisenberg limit. The concurrent multiplenquasi-phase-matchings provided by the nonlinear photonic crystal open up a way to integrated quantum lightnsources.