Sub-- and super--fidelity as bounds for quantum fidelity

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dc.creatorMiszczak, J. A.
dc.creatorPuchała, Z.
dc.creatorHorodecki, P.
dc.creatorUhlmann, A.
dc.creatorŻyczkowski, K.
dc.date2008-05-14
dc.date2008-11-19
dc.date.accessioned2026-07-07T10:19:02Z
dc.date.available2026-07-07T10:19:02Z
dc.descriptionWe derive several bounds on fidelity between quantum states. In particular we show that fidelity is bounded from above by a simple to compute quantity we call super--fidelity. It is analogous to another quantity called sub--fidelity. For any two states of a two--dimensional quantum system (N=2) all three quantities coincide. We demonstrate that sub-- and super--fidelity are concave functions. We also show that super--fidelity is super--multiplicative while sub--fidelity is sub--multiplicative and design feasible schemes to measure these quantities in an experiment. Super--fidelity can be used to define a distance between quantum states. With respect to this metric the set of quantum states forms a part of a $N^2-1$ dimensional hypersphere.
dc.description22 pages, 4 figures
dc.identifierhttps://arxiv.org/abs/0805.2037
dc.identifierhttp://arxiv.org/abs/0805.2037
dc.identifierQuantum Information & Computation, Vol.9 No.1&2 (2009)
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/174366
dc.subjectQuantum Physics
dc.titleSub-- and super--fidelity as bounds for quantum fidelity
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