  We describe a feasible logic Bell-state analysis protocol by employing the
logic entanglement to be the robust concatenated Greenberger-Horne-Zeilinger
(C-GHZ) state. This protocol only uses polarization beam splitters and
half-wave plates, which are available in current experimental technology. We
can conveniently identify two of the logic Bell states. This protocol can be
easily generalized to the arbitrary C-GHZ state analysis. We can also
distinguish two $N$-logic-qubit C-GHZ states. As the previous theory and
experiment both showed that the C-GHZ state has the robustness feature, this
logic Bell-state analysis and C-GHZ state analysis may be essential for
linear-optical quantum computation protocols whose building blocks are
logic-qubit entangled state.
