Nonlinear coupler operating on Werner-like states - entanglement   creation, its enhancement and preservation
  We discuss a model of two nonlinear Kerr-like oscillators, mutually coupled and excited by parametric process. We show that the system's evolution, starting from Werner-like states, remains closed within a small set of two-mode n-photon states the system, and pure two-qubit entangled state can be generated. For some initial Werner-like states delayed entanglement generation can be observed. We investigate the influence of two damping mechanisms on the system's evolution. We show that for the both cases, the entanglement can survive despite the presence of damping, and the effects of sudden entanglement death and its rebirth can appear in the system. 
A. Kowalewska-Kud{\l}aszyk and W. Leo\'nski
quant-ph