Entanglement witness measurement for two-qubit states by optical interferenceZhi-Wei Wang, Jian Li, Yun-Feng Huang, Yong-Sheng Zhang, Xi-Feng Ren, Pei Zhang and Guang-Can GuoEPL, 82 6 (2008) 60003DOI: https://doi.org/10.1209/0295-5075/82/60003