  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.
