Quantum steering ellipsoids, extremal physical states and monogamy

Milne, Antony; Jevtic, Sania; Jennings, David; Wiseman, Howard and Rudolph, Terry. 2014. Quantum steering ellipsoids, extremal physical states and monogamy. New Journal of Physics, 16, ISSN 1367-2630 [Article]

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Abstract or Description

Any two-qubit state can be faithfully represented by a steering ellipsoid inside the Bloch sphere, but not every ellipsoid inside the Bloch sphere corresponds to a two-qubit state. We give necessary and sufficient conditions for when the geometric data describe a physical state and investigate maximal volume ellipsoids lying on the physical-unphysical boundary. We derive monogamy relations for steering that are strictly stronger than the Coffman–Kundu–Wootters (CKW) inequality for monogamy of concurrence. The CKW result is thus found to follow from the simple perspective of steering ellipsoid geometry. Remarkably, we can also use steering ellipsoids to derive non-trivial results in classical Euclidean geometry, extending Eulerʼs inequality for the circumradius and inradius of a triangle.

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28 March 2014Submitted
6 June 2014Accepted
7 August 2014Published

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25 Oct 2018 15:55

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29 Apr 2020 16:56

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Yes, this version has been peer-reviewed.



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