%0 Journal Article
%T Optimal minimal measurements of mixed states
%A G. Vidal
%A J. I. Latorre
%A P. Pascual
%A R. Tarrach
%J Physics
%D 1998
%I arXiv
%R 10.1103/PhysRevA.60.126
%X The optimal and minimal measuring strategy is obtained for a two-state system prepared in a mixed state with a probability given by any isotropic a priori distribution. We explicitly construct the specific optimal and minimal generalized measurements, which turn out to be independent of the a priori probability distribution, obtaining the best guesses for the unknown state as well as a closed expression for the maximal mean averaged fidelity. We do this for up to three copies of the unknown state in a way which leads to the generalization to any number of copies, which we then present and prove.
%U http://arxiv.org/abs/quant-ph/9812068v2