Validation of entanglement purification by continuous variable   polarization
  We investigate the possibility of characterizing two-party entanglement by measuring correlations of Stokes operators in polarized bright light beams. We adapt a general separability criterion to such operators. We then show that entanglement purification can only be singled out for a particular protocol. 
Francesca Alessandrini, Stefano Mancini, and Paolo Tombesi