Optimal weak value measurements: Pure states
| Autor: | Dass, N. D. Hari, Krishna, R. Rajath, Samantaray, Sai Smruti |
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| Rok vydání: | 2017 |
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| Druh dokumentu: | Working Paper |
| Popis: | We apply the notion of \emph{optimality} of measurements for state determination(tomography) as originally given by Wootters and Fields to \emph{weak value tomography} of \emph{pure states}. They defined measurements to be optimal if they 'minimised' the effects of statistical errors. For technical reasons they actually maximised the state averaged information, precisely quantified as the negative logarithm of 'error volume'. In this paper we optimise both the state averaged information as well as error volumes. We prove, for Hilbert spaces of arbitrary (finite) dimensionality, that varieties of weak value measurements are optimal when the post-selected bases are \emph{mutually unbiased} with respect to the eigenvectors of the observable being measured. We prove a number of important results about the geometry of state spaces when expressed through the weak values as coordinates. We derive an expression for the Ka\"ehler potential for the N-dimensional case with the help of which we give an exact treatment of the arbitrary-spin case. Comment: 13 pages in JHEP style. A new feature in this, hopefully, last revision is a proof based the Wootters-Fields information. Many typos corrected and the solution of the arbitrary spin case made exact with the help of Kaehler potential. New technical details added. Manuscript made compact and bibliography cleaned up |
| Databáze: | arXiv |
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