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Estimating the expectation values of spin-1/2 observables with finite resources

Brougham, Thomas and Andersson, Erika (2007) Estimating the expectation values of spin-1/2 observables with finite resources. Physical Review A, 76 (5). 052313. ISSN 1050-2947

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Abstract

We examine the problem of estimating the expectation values of two observables when we have a finite number of copies of an unknown qubit state. Specifically we examine whether it is better to measure each of the observables separately on different copies or to perform a separable nonadaptive joint measurement of the observables on each copy. We find that joint measurements can sometimes provide an advantage over separate measurements, but only if we make estimates of an observable based solely on the results of measurements of that observable. If we instead use both sets of results to estimate each observable then we find that individual measurements will be better. Finally we consider estimating the expectation values of three complementary observables for an unknown qubit.

Item type: Article
ID code: 6203
Keywords: qubit state, expectation values, physics, joint measurement, quantum, observables, finite resources, Optics. Light, Atomic and Molecular Physics, and Optics
Subjects: Science > Physics > Optics. Light
Department: Faculty of Science > Physics
Depositing user: Miss Darcy Spiller
Date Deposited: 02 Jun 2008
Last modified: 15 Apr 2015 11:01
Related URLs:
URI: http://strathprints.strath.ac.uk/id/eprint/6203

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