Interplay between interaction and (un)correlated disorder in one-dimensional many-particle systems: delocalization and global entanglement

TL;DR

This study explores how interaction and disorder influence localization and entanglement in one-dimensional quantum many-body systems, revealing complex behaviors and conditions under which disorder can either delocalize or localize particles.

Contribution

It provides a comprehensive analysis of the combined effects of interaction and correlated versus uncorrelated disorder on localization and entanglement in various 1D quantum models.

Findings

Maximum delocalization occurs when particles do not interact in clean chains.

Multi-partite entanglement peaks in the chaotic regime with certain interactions.

Correlated disorder can extend two-particle states but may enhance localization with strong interactions.

Abstract

We consider a one-dimensional quantum many-body system and investigate how the interplay between interaction and on-site disorder affects spatial localization and quantum correlations. The hopping amplitude is kept constant. To measure localization, we use the number of principal components (NPC), which quantifies the spreading of the system eigenstates over vectors of a given basis set. Quantum correlations are determined by a global entanglement measure $Q$, which quantifies the degree of entanglement of multipartite pure states. Our studies apply analogously to a one-dimensional system of interacting spinless fermions, hard-core bosons, or yet to an XXZ Heisenberg spin-1/2 chain. Disorder is characterized by both: uncorrelated and long-range correlated random on-site energies. Dilute and half-filled chains are analyzed. In half-filled clean chains, delocalization is maximum when the particles do not interact, whereas multi-partite entanglement is largest when they do. In the presence of uncorrelated disorder, NPC and Q show a non-trivial behavior with interaction, peaking in the chaotic region. The inclusion of correlated disorder may further extend two-particle states, but the effect decreases with the number of particles and strength of their interactions. In half-filled chains with large interaction, correlated disorder may even enhance localization.