Quantitative complementarity between local and nonlocal character of   quantum states in a three-qubit system
  Local or nonlocal character of quantum states can be quantified and is subject to various bounds that can be formulated as complementarity relations. Here, we investigate the local vs. nonlocal character of pure three-qubit states by a four-way interferometer. The complete entanglement in the system can be measured as the entanglement of a specific qubit with the subsystem consisting of the other two qubits. The quantitative complementarity relations are verified experimentally in an NMR quantum information processor. 
Xinhua Peng, Jingfu Zhang, Jiangfeng Du and Dieter Suter