  We study a limited set of optical circuits for creating near maximal
polarisation entanglement {\em without} the usual large vacuum contribution.
  The optical circuits we consider involve passive interferometers,
feed-forward detection, down-converters and squeezers. For input vacuum fields
we find that the creation of maximal entanglement using such circuits is
impossible when conditioned on two detected auxiliary photons. So far, there
have been no experiments with more auxiliary photons. Thus, based on the
minimum complexity of the circuits required, if near maximal polarisation
entanglement is possible it seems unlikely that it will be implemented
experimentally with the current resources.
