  We implement experimentally a deterministic method to prepare and measure so
called single-photon two-qubit entangled states or single-photon Bell-states,
in which the polarization and the spatial modes of a single-photon each
represent a quantum bit. All four single-photon Bell-states can be easily
prepared and measured deterministically using linear optical elements alone. We
also discuss how this method can be used for recently proposed single-photon
two-qubit quantum cryptography protocol.
