Quantifying nonclassical correlation via the generalized Wigner-Yanase skew information

Abstract

Nonclassical correlation is an important concept in quantum information theory, referring to a special type of correlation that exists between quantum systems, which surpasses the scope of classical physics. In this paper, we introduce the concept of a family of information with important properties, namely the generalized Wigner-Yanase skew information, of which the famous quantum Fisher information and Wigner-Yanase-Dyson skew information are special cases. We classify the local observables into two categories (i.e., orthonormal bases and Hermitian operators with a fixed nondegenerate spectrum), and based on this, we propose several indicators to quantify nonclassical correlation of bipartite quantum states. We have not only investigated some important properties of these indicators but also illustrated through specific examples that they can indeed capture nonclassical correlation. Furthermore, we find that these indicators reduce to entanglement measure for bipartite pure states. Specifically, we also derive the relationship between these indicators and the entanglement measure known as $I$-concurrence.