Many-body mobility edge due to symmetry-constrained dynamics and strong interactions

TL;DR

This paper demonstrates the existence of a many-body mobility edge in a disordered spin model, showing how symmetry constraints and interactions lead to tunable localization-delocalization transitions.

Contribution

It provides numerical and analytical evidence for a many-body mobility edge arising from symmetry-constrained excitations in an anisotropic spin model.

Findings

Presence of a tunable many-body mobility edge.

Different dynamics in ferromagnetic and antiferromagnetic regimes.

Weak disorder can shift the mobility edge.

Abstract

We provide numerical evidence combined with an analytical understanding of the many-body mobility edge for the strongly anisotropic spin-1/2 XXZ model in a random magnetic field. The system dynamics can be understood in terms of symmetry-constrained excitations about parent states with ferromagnetic and anti-ferromagnetic short range order. These two regimes yield vastly different dynamics producing an observable, tunable many-body mobility edge. We compute a set of diagnostic quantities that verify the presence of the mobility edge and discuss how weakly correlated disorder can tune the mobility edge further.