Entanglement witness measurement for two-qubit states by optical interferenceZhi-Wei Wang1, Jian Li2, Yun-Feng Huang1, Yong-Sheng Zhang1, Xi-Feng Ren1, Pei Zhang1 and Guang-Can Guo1
1 Key Laboratory of Quantum Information, University of Science and Technology of China, CAS Hefei 230026, PRC
2 Department of Physics, Southeast University - Nanjing 211189, PRC
received 10 March 2008; accepted in final form 22 April 2008; published June 2008
published online 30 May 2008
We present a novel interferometer to directly implement entanglement witness measurement. This is optimal and avoids the complex task to decompose witness into local projectors. The interferometer is based on a hybrid realization of controlled-SWAP gate. We also demonstrate entanglement-witness for simple cases experimentally.
03.67.Mn - Entanglement measures, witnesses, and other characterizations.
42.50.Dv - Quantum states engineering and measurements.
42.65.Lm - Parametric down conversion and production of entangled photons.
© EPLA 2008