  We propose an efficient scheme for the generation of three-photon
Greenberger-Horne-Zeilinger (GHZ) state with linear optics and postselection.
Several devices are designed and a two-mode quantum nondemolition (QND)
detection is introduced to obtain the desired state. It is worth noting that
the states which have entanglement in both polarization and spatial degrees of
freedom are created in one of the designed setups. The method described in the
present scheme can create a large number of three-photon GHZ states in
principle. We also discuss an approach to generate the desired GHZ state in the
presence of channel noise.
