Volume 82, Number 6, June 2008
Article Number 60003
Number of page(s) 4
Section General
Published online 30 May 2008
EPL, 82 (2008) 60003
DOI: 10.1209/0295-5075/82/60003

Entanglement witness measurement for two-qubit states by optical interference

Zhi-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