Geometric representation of two-qubit entanglement witnesses

Milne, Antony; Jennings, David and Rudolph, Terry. 2015. Geometric representation of two-qubit entanglement witnesses. Physical Review A, 92(012311), ISSN 2469-9926 [Article]

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Abstract or Description

Any two-qubit state can be represented geometrically by a steering ellipsoid inside the Blochsphere. We extend this approach to represent any block positive two-qubit operator B. We derive a classification scheme based on the positivity of detBand de t B T B; this shows that any ellipsoid inside the Bloch sphere must represent either a two-qubit state or a two-qubit entanglement witness. We focus on such witnesses and their corresponding ellipsoids, finding that properties such as witness optimality are naturally manifest in this geometric representation

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10 July 2015Published

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13 Nov 2018 16:23

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29 Apr 2020 16:56


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