Optical Bell state and Greenberger–Horne–Zeilinger-state analyzers through the cavity input–output process

With the ancillary one-sided cavities each trapping an alkali atom, the schemes for the analyzers of two-photon Bell states and three-photon Greenberger–Horne–Zeilinger (GHZ) states are proposed, respectively. Moreover, all of two-photon Bell states and three-photon GHZ states can be nondestructively distinguished. The influence of atomic spontaneous emission and output coupling inefficiency are discussed.