Entanglement of multiphoton states in polarization and quadrature variables
A brief overview of entanglement characterization is given in the cases of biphoton and
multiphoton polarization states. The importance of the approach is stressed based on the
Schmidt decomposition. This method is applied to the characterization of the quadrature
entanglement in two-mode multiphoton states. The fruitfulness of this approach is illustrated
by a series of examples.