Unitary measurements of discrete quantities in quantum mechanics

Abstract

The pure measurements of discrete physical quantities are characterized within quantum theory of measurement and their unitary representations are given. Probabilistic aspects of measurements related to the so-called strong correlation conditions and a probabilistic characterization of the first kind measurements are examined. The problem of the objectification of the measurement result is analyzed in terms of a classical behavior of the measuring apparatus. As a by-product a generalization of the Wigner–Araki–Yanase theorem is given.