Entanglement concentration for unknown atomic entangled states via   entanglement swapping
  An entanglement concentration scheme for unknown atomic entanglement states is proposed via entanglement swapping in cavity QED. Because the interaction used here is a large-detuned one between two driven atoms and a quantized cavity mode, the effects of the cavity decay and thermal field have been eliminated. These advantages can warrant the experimental feasibility of the current scheme. 
Ming Yang, Yan Zhao, Wei Song and Zhuo-Liang Cao