Recently, experiments showed that the spatial-mode states of entangledphotons are more robust than their polarization-mode states in quantumcommunications. Here we construct a complete and deterministic protocol foranalyzing the spatial Bell states using the interaction between a photon and anelectron spin in a charged quantum dot inside a one-side micropillarmicrocavity. A quantum nondemolition detector (QND) for checking the parity ofa two-photon system can be constructed with the giant optical Faraday rotationin this solid state system. With this parity-check QND, we present a completeand deterministic proposal for the analysis of the four spatial-mode Bellstates. Moreover, we present a robust two-step quantum secure directcommunication protocol based on the spatial-mode Bell states and the photonicspatial Bell-state analysis. Our analysis shows that our BSA proposal works inboth the strong and the weak coupling regimes if the side leakage and cavityloss rate is small.
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