Experimental Entanglement Distillation of Two-qubit Mixed States Under   Local filtering Operations
  We experimentally demonstrate optimal entanglement distillation from two forms of two-qubit mixed states under local filtering operations according to the constructive method intruduced by F. Verstraete et al. [Phys. Rev. A 64, 010101(R) (2001)]. In principle, our set-up can be easily applied to distilling entanglement from arbitrary two-qubit partially mixed states. We also test the violation of the Clauser-Horne-Shinmony-Holt (CHSH) inequality for the distilled state from the first form of mixed state to show its "hidden non-locality". 
Zhi-Wei Wang, Xiang-Fa Zhou, Yun-Feng Huang, Yong-Sheng Zhang, Xi-Feng   Ren and Guang-Can Guo