  We demonstrate that the key to realizing arbitrary control over pairs of
polarization states of light, i.e. transforming an arbitrarily polarized pair
of input states to an arbitrarily polarized pair of output states, is the
ability to generate pairs of states with orthogonal polarizations from
non-orthogonal pairs of initial states. We then develop a new class of
non-Hermitian meta-materials, termed complex birefringent meta-materials, which
are able to do exactly this. Such materials could facilitate the detection of
small polarization changes in scattering experiments, as well as enable new
polarization multiplexing schemes in communications networks.
