Strongly entangled light from planar microcavities
  The emission of entangled light from planar semiconductor microcavities is studied and the entanglement properties are analyzed and quantified. Phase-matching of the intra-cavity scattering dynamics for multiple pump beams or pulses, together with the coupling to external radiation, leads to the emission of a manifold of entangled photon pairs. A decomposition of the emitted photons into two parties leads to a strong entanglement of the resulting bipartite system. For the quantification of the entanglement, the Schmidt number of the system is determined by the construction of Schmidt number witnesses. It is analyzed to which extend the resources of the originally strongly entangled light field are diminished by dephasing in propagation channels. 
D. Pagel, H. Fehske, J. Sperling, and W. Vogel
quant-ph