  We propose and experimentally demonstrate that a Mach-Zehnder interferometer
composed of polarized beam splitters and a pentaprism in the place of one of
the mirrors works as a linear optical quantum controlled-NOT (CNOT) gate. To
perform the information processing, the polarization and orbital angular
momentum (OAM) of the photons act as the control and target qubits,
respectively. The readout process is simple, requiring only a linear polarizer
and a triangular diffractive aperture before detection. The viability and
stability of the experiment makes the present proposal a valuable candidate for
future implementations in optical quantum computation protocols.
