title: Invariant information and quantum state estimation.
abstract: The invariant information, introduced by C. Brukner and A. Zeilinger [Phys. Rev. Lett. 83, 3354 (1999)], is reconsidered from the point of view of quantum state estimation. We show that this quantity is directly related to the mean error of the standard reconstruction from the measurement of a complete set of mutually complementary observables. We give its generalization in terms of the Fisher information. Provided that the optimum reconstruction is adopted, the information loses its invariant character.
authors.affiliation: Department of Optics, Palacky University, 17. listopadu 50, 772 00 Olomouc, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Rehácek
authors.forename: Z
authors.initials: Z
authors.lastname: Hradil