  We propose a class of preparation schemes for orbital angular momentum and
polarisation qubits carried by single photons or classical states of light
based on coherent feedback control by an ancillary degree of freedom of light.
The preparation methods use linear optics and include the transcription of an
arbitrary polarisation state onto a two-level OAM system (swap) for arbitrary
OAM values plus/minus "l" within a light beam, i.e. without spatial
interferometer. The preparations can be carried out with unit efficiency
independent from the potentially unknown initial state of the system. Moreover,
we show how to translate measurement-based qubit control channels into coherent
feedback schemes for optical implementation.
