Disorder-assisted distribution of entanglement in $XY$ spin chains

TL;DR

This paper investigates how correlated disorder in $XY$ spin chains influences entanglement creation and distribution, revealing that such disorder can enhance long-range entanglement and improve quantum information transmission.

Contribution

It demonstrates that long-range correlated disorder can facilitate entanglement spread and transmission in spin chains, offering insights for quantum device design under realistic disorder conditions.

Findings

Correlated disorder leads to extended modes enabling long-range entanglement.

Disorder can enhance pairwise entanglement between distant spins.

Correlated disorder improves quantum state transmission compared to uncorrelated cases.

Abstract

We study the creation and distribution of entanglement in disordered $XY$-type spin-$1/2$ chains for the paradigmatic case of a single flipped spin prepared on a fully polarized background. The local magnetic field is set to follow a disordered long-range-correlated sequence with power-law spectrum. Depending on the degree of correlations of the disorder, a set of extended modes emerge in the middle of the band yielding an interplay between localization and delocalization. As a consequence, a rich variety of entanglement distribution patterns arises, which we evaluate here through the concurrence between two spins. We show that, even in the presence of disorder, the entanglement wave can be pushed to spread out reaching distant sites and also enhance pairwise entanglement between the initial site and the rest of the chain. We also study the propagation of an initial maximally-entangled state through the chain and show that correlated disorder improves the transmission quite significantly when compared with the uncorrelated counterpart. Our work contributes in designing solid-state devices for quantum information processing in the realistic setting of correlated static disorder.