Polarization entanglement distillation through local filtering operations

An entanglement distillation scheme is proposed for an amplitude-damped polarization-entangled photon states via local filtering operations. The local filtering operations, i.e. positive operator-valued measure, on photons are realized by a series of Brewster window pairs. The entanglement of the survived photon pairs in the scheme will be much larger than that of the initial ones. In this sense, this distillation scheme is better than the currently existing entanglement protection scheme, where only the entanglement decaying time is prolonged and the entanglement is not enhanced at all. In addition, this scheme is simple and feasible within the current linear optical techniques.