Components of optical qubits encoded in sideband modes

We describe a scheme for the encoding and manipulation of single photon qubits in optical sideband modes using standard optical elements. We propose and analyze the radio frequency half-wave plate, which may be used to make arbitrary rotations of a state in the frequency basis, and the frequency beamsplitter, which may be used to separate (or combine) photons of different frequencies into (from) different spatial modes.