Nonclassicality and criticality in symmetry-protected magnetic phases

TL;DR

This paper investigates quantum and global discord in a spin-1 Heisenberg chain with single-ion anisotropy, revealing their ability to detect phase transitions, exhibit critical scaling, and show unexpected temperature behavior.

Contribution

It demonstrates that quantum discord measures can identify quantum phase transitions and exhibit universal critical scaling in symmetry-protected magnetic phases.

Findings

Quantum discord detects phase transitions in the Haldane phase.

Quantum discord shows critical scaling with universal exponents.

Quantum discord can increase with temperature in thermal states.

Abstract

Quantum and global discord in a spin-1 Heisenberg chain subject to single-ion anisotropy (uniaxial field) are studied using exact diagonalisation and the density matrix renormalisation group (DMRG). We find that these measures of quantum nonclassicality are able to detect the quantum phase transitions confining the symmetry protected Haldane phase and show critical scaling with universal exponents. Moreover, in the case of thermal states, we find that quantum discord can increase with increasing temperature.