A Generalized Geometric Measurement of Quantum Discord: Exact Treatment

TL;DR

This paper introduces a generalized geometric measure of quantum discord based on Hellinger distance, offering exact solutions for certain states and applications in quantum phase transition detection.

Contribution

It presents a new, computable, and measurement-independent geometric quantum discord measure that extends to multipartite states and addresses previous critiques.

Findings

Exact results for bipartite pure states using Schmidt decomposition

Exact solutions for certain bipartite mixed states

Application to detecting quantum phase transitions in specific models

Abstract

A generalization of the geometric measure of quantum discord is introduced in this article, based on Hellinger distance. Our definition has virtues of computability and independence of local measurement. In addition it also does not suffer from the recently raised critiques about quantum discord. The exact result can be obtained for bipartite pure states with arbitrary levels, which is completely determined by the Schmidt decomposition. For bipartite mixed states the exact result can also be found for a special case. Furthermore the generalization into multipartite case is direct. It is shown that it can be evaluated exactly when the measured state is invariant under permutation or translation. In addition the detection of quantum phase transition is also discussed for Lipkin-Meshkov-Glick and Dicke model.