Enhancement of Quantum Correlation Length in Quenched Disordered Spin Chains

TL;DR

This paper investigates how quenched disorder affects quantum correlations in spin chains, finding that while entanglement length remains unchanged, quantum discord length increases significantly, indicating enhanced quantum correlations.

Contribution

It demonstrates that quenched disorder can significantly enhance quantum discord length without affecting entanglement length in spin chains.

Findings

Quantum discord length increases with quenched disorder.

Entanglement length remains unchanged by disorder.

Disorder enhances long-range quantum correlations.

Abstract

Classical correlations of ground states typically decay exponentially and polynomially, respectively for gapped and gapless short-ranged quantum spin systems. In such systems, entanglement decays exponentially even at the quantum critical points. However, quantum discord, an information-theoretic quantum correlation measure, survives long lattice distances. We investigate the effects of quenched disorder on quantum correlation lengths of quenched averaged entanglement and quantum discord, in the anisotropic XY and XYZ spin glass and random field chains. We find that there is virtually neither reduction nor enhancement in entanglement length while quantum discord length increases significantly with the introduction of the quenched disorder.