Separable States can be used to distribute entanglement.
We show that no entanglement is necessary to distribute entanglement; that is, two distant particles can be entangled by sending a third particle that is never entangled with the other two. Similarly, two particles can become entangled by continuous interaction with a highly mixed mediating particle that never itself becomes entangled. We also consider analogous properties of completely positive maps, in which the composition of two separable maps can create entanglement.
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Max Planck Institut für Quantenoptik, Hans-Kopfermann Strasse 1, D-85748 Garching, Germany.
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Cirac
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