Quantum correlations in topological quantum phase transitions

TL;DR

This paper investigates quantum correlations in a 2D topological system, revealing that local spins are classically correlated while quantum correlations are global, with critical behavior observed at the phase transition.

Contribution

It demonstrates the distinct distribution of quantum correlations in topologically ordered systems and analyzes their critical behavior using quantum discord.

Findings

Local spins are classically correlated.

Quantum correlations are hidden in the global lattice.

Mutual information and global quantum discord show critical behavior.

Abstract

We study the quantum correlations in a 2D system that possesses a topological quantum phase transition. The quantumness of two-body correlations is measured by quantum discord. We calculate both the correlation of two local spins and that of an arbitrary spin with the rest of the lattice. It is notable that local spins are classically correlated, while the quantum correlation is hidden in the global lattice. This is different from other systems which are not topologically orderd. Moreover, the mutual information and global quantum discord show critical behavior in the topological quantum phase transition.