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Solution to the Mean King's problem with mutually unbiased bases for arbitrary levels

Gen Kimura·Hajime Tanaka·Masanao Ozawa
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Abstract

The Mean King's problem with mutually unbiased bases is reconsidered for arbitrary d-level systems. Hayashi, Horibe and Hashimoto [Phys. Rev. A 71, 052331 (2005)] related the problem to the existence of a maximal set of d-1 mutually orthogonal Latin squares, in their restricted setting that allows only measurements of projection-valued measures. However, we then cannot find a solution to the problem when e.g., d=6 or d=10. In contrast to their result, we show that the King's problem always has a solution for arbitrary levels if we also allow positive operator-valued measures. In constructing the solution, we use orthogonal arrays in combinatorial design theory.

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Gen Kimura, Hajime Tanaka, Masanao Ozawa. 2006-04-13. Solution to the Mean King's problem with mutually unbiased bases for arbitrary levels. https://doi.org/10.1103/physreva.73.050301

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