Abstract
The invariant information, introduced by Č. 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.
- Received 30 November 2001
DOI:https://doi.org/10.1103/PhysRevLett.88.130401
©2002 American Physical Society
