Entanglement of assistance and multipartite state distillation

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dc.creatorSmolin, John A.
dc.creatorVerstraete, Frank
dc.creatorWinter, Andreas
dc.date2005-05-06
dc.date.accessioned2026-07-07T06:32:16Z
dc.date.available2026-07-07T06:32:16Z
dc.descriptionWe find that the asymptotic entanglement of assistance of a general bipartite mixed state is equal to the smaller of its two local entropies. Our protocol gives rise to the asymptotically optimal EPR pair distillation procedure for a given tripartite pure state, and we show that it actually yields EPR and GHZ states; in fact, under a restricted class of protocols, which we call "one-way broadcasting", the GHZ-rate is shown to be optimal. This result implies a capacity theorem for quantum channels where the environment helps transmission by broadcasting the outcome of an optimally chosen measurement. We discuss generalisations to m parties, and show (for m=4) that the maximal amount of entanglement that can be localised between two parties is given by the smallest entropy of a group of parties of which the one party is a member, but not the other. This gives an explicit expression for the asymptotic localisable entanglement, and shows that any nontrivial ground state of a spin system can be used as a perfect quantum repeater if many copies are available in parallel. Finally, we provide evidence that any unital channel is asymptotically equivalent to a mixture of unitaries, and any general channel to a mixture of partial isometries.
dc.description11 pages revtex4, 1 hand-drawn eps figure
dc.identifierhttps://arxiv.org/abs/quant-ph/0505038
dc.identifierhttp://arxiv.org/abs/quant-ph/0505038
dc.identifierPhys. Rev. A, vol. 72, 052317, 2005
dc.identifierdoi:10.1103/PhysRevA.72.052317
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/98849
dc.subjectQuantum Physics
dc.titleEntanglement of assistance and multipartite state distillation
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