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Parameter estimation for mixed states from a single copy

Thomas Konrad·Otfried Gühne·Jürgen Audretsch·Hans J. Briegel
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Abstract

Given a single copy of a mixed state of the form ρ=λρ_1+(1-λ)ρ_2, what is the optimal measurement to estimate the parameter λ, if ρ_1 and ρ_2 are known? We present a general strategy to obtain the optimal measurements employing a Bayesian estimator. The measurements are chosen to minimize the deviation between the estimated- and the true value of λ. We explicitly determine the optimal measurements for a general two-dimensional system and for important higher dimensional cases.

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Thomas Konrad, Otfried Gühne, Jürgen Audretsch, Hans J. Briegel. 2007-05-08. Parameter estimation for mixed states from a single copy. https://doi.org/10.1103/physreva.75.062101

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