Wigner-Yanase skew information and entanglement generation in quantum measurement

Abstract

The first step of quantum measurement procedure is known as \emph{premeasurement}, during when correlation between measuring system and measurement apparatus is established. One compelling non-classical correlation is entanglement, a useful resource for various quantum information theoretic protocols. Quantifying the amount of entanglement in the premeasurement state, therefore, seeks importance from practical ground and this is the central issue of the present paper. Interestingly, for a two-label quantum system we obtain that the amount of entanglement, measured in term of \emph{negativity}, generated in premeasurement process is actually quantified by two factors: \emph{skew information} between system's initial state and the measurement direction, which quantifies the amount of information on the values of observables not commuting with the conserved quantity of the system, and \emph{mixedness parameter} of the system's initial state.