  A SWAP operation between different types of qubits of single photons is
essential for manipulating hyperentangled photons for a variety of
applications. We have implemented an efficient SWAP gate for the momentum and
polarization degrees of freedom of single photons. The SWAP gate was utilized
in a single-photon two-qubit quantum logic circuit to deterministically
transfer momentum entanglement between a pair of down-converted photons to
polarization entanglement. The polarization entanglement thus obtained violates
Bell's inequality by more than 150 standard deviations.
