Analytic Formulas for Quantum Discord of Special Families of N-Qubit States

TL;DR

This paper derives exact formulas for quantum discord in specific N-qubit states, including generalized GHZ states, and reveals a discord freezing phenomenon in even-qubit systems under phase flip decoherence.

Contribution

It provides the first analytical formulas for quantum discord in certain N-qubit states and identifies a discord freezing effect under decoherence.

Findings

Exact formulas for quantum discord in various N-qubit states.

Discovery of discord freezing in even-qubit systems under phase flip decoherence.

Enhanced understanding of quantum correlations in multipartite systems.

Abstract

Quantum discord, a key indicator of non-classical correlations in bipartite systems, has been recently extended to multipartite scenarios [Phys. Rev. Lett. 2020, 124:110401]. We present exact analytic formulas for the quantum discord of special families of N-qubit states, including generalized class of GHZ states. Our formulations span $2$, $3$, $4n$, $4n+1$, $4n+2$, and $4n+3$-qubit configurations where $n\in 1, 2, \ldots$, which refine the assessment of quantum correlations and provide an analytical tool in quantum computation. Moreover, we uncover a ``discord freezing'' in even-qubit systems under phase flip decoherence which provides a means for preserving quantum coherence in environmental perturbations.