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On exposed positive maps: Robertson and Breuer-Hall maps

Quantum Physics 2011-08-11 v1 Mathematical Physics math.MP

Abstract

It is well known that so called Breuer-Hall positive maps used in entanglement theory are optimal. We show that these maps possess much more subtle property --- they are exposed. As a byproduct it proves that a Robertson map in the algebra of 4 x 4 complex matrices is not only extreme, which was already shown by Robertson, but also exposed.

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Cite

@article{arxiv.1108.2233,
  title  = {On exposed positive maps: Robertson and Breuer-Hall maps},
  author = {Dariusz Chruściński},
  journal= {arXiv preprint arXiv:1108.2233},
  year   = {2011}
}

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7 pages