Stable dynamic helix state in the nonintegrable XXZ Heisenberg model

TL;DR

This paper explores how external fields affect the stability of spin helix states in a nonintegrable XXZ Heisenberg model, revealing conditions under which these states behave as quantum scars and their robustness in chaotic regimes.

Contribution

It demonstrates the impact of transverse and uniform z fields on the stability and dynamical behavior of helix states, providing new insights into quantum scars in nonintegrable systems.

Findings

Random transverse fields induce transition to nonintegrability.

Uniform z field enhances the dynamical stability of helix states.

Entanglement entropy indicates scar extent is unaffected by z field in chaotic regimes.

Abstract

We investigate the influence of external fields on the stability of spin helix states in an XXZ Heisenberg model. Exact diagonalization on a finite system shows that random transverse fields in the x and y directions drive the transition from integrability to nonintegrability. In such a system, the helix state can be regarded as a quantum scar. Simultaneously, the presence of uniform z field enables the helix state to better maintain its dynamical nature, allowing for a clearer understanding of its evolutionary behavior. However, the entanglement entropy reveals that irrespective of the presence of a uniform z field, as long as the system remains chaotic, the scar extent of the helix state shows no significant variation.