Coexistence of qubit effects

Paul Busch; Heinz-Jürgen Schmidt

doi:10.1007/s11128-009-0109-x

Coexistence of qubit effects

Paul Busch, Heinz-Jürgen Schmidt

Mathematics

Research output: Contribution to journal › Article › peer-review

Abstract

Two quantum events, represented by positive operators (effects), are coexistent if they can occur as possible outcomes in a single measurement scheme. Equivalently, the corresponding effects are coexistent if and only if they are contained in the ranges of a single (joint) observable. Here we give several equivalent characterizations of coexistent pairs of qubit effects. We also establish the equivalence between our results and those obtained independently by other authors. Our approach makes explicit use of the Minkowski space geometry inherent in the four-dimensional real vector space of selfadjoint operators in a two-dimensional complex Hilbert space.

Original language	English
Pages (from-to)	143-169
Number of pages	26
Journal	Quantum Information Processing
Volume	9
Issue number	2
DOIs	https://doi.org/10.1007/s11128-009-0109-x
Publication status	Published - Apr 2010

Bibliographical note

© Springer Science+Business Media, LLC 2009. This is an author produced version of a paper published in 'Quantum Information Processing'. Uploaded in accordance with the publisher's self-archiving policy.

Keywords

quantum observables
joint measurability
coexistence
qubit

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10.1007/s11128-009-0109-x

BuschSchmidt coex20090105
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http://www.springerlink.com/content/4983378717786807/

Cite this

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Coexistence of qubit effects

Abstract

Bibliographical note

Keywords

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