Creating and probing macroscoping entanglement with light
  We describe a scheme showing signatures of macroscopic optomechanical entanglement generated by radiation pressure in a cavity system with a massive movable mirror. The system we consider reveals genuine multipartite entanglement. We highlight the way the entanglement involving the inaccessible massive object is unravelled, in our scheme, by means of field-field quantum correlations. 
M. Paternostro, D. Vitali, S. Gigan, M. S. Kim, C. Brukner, J. Eisert,   M. Aspelmeyer