Deterministic Entanglement Extraction

We propose a scheme for a deterministic extraction of entanglement by means of a reduction process involving local von Neumann measurements. In an example of a tripartite system, we show that by choosing appropriate measurement bases for a given qubit, one can map an initial three-qubit state into outcome pure bipartite states with the same amount of entanglement of formation. In addition, by optimizing local projective measurements, one can efficiently convert higher-order correlations, contained in a multipartite state, into their lower-order counterparts, and thus significantly enhance the initial (reduced mixed-state) entanglement. We find the analytical expressions for the bounds of the deterministically extracted entanglement and relate them with the initial three-tangle and bipartite (mixed-state) concurrences.