Exploring electron spin dynamics in spin chains using defects as a quantum probe

TL;DR

This paper studies electron spin dynamics in topological defect states of dimerized spin chains, revealing relaxation mechanisms and proposing design principles to enhance coherence for quantum device applications.

Contribution

It provides a detailed analysis of spin relaxation and decoherence sources in dimerized spin chains, introducing strategies to improve coherence times in quantum systems.

Findings

Relaxation dominated by phonon-bottleneck at low temperatures.

High-temperature relaxation governed by the dimerization gap.

Inter edge-state dipolar field reduction extends coherence time.

Abstract

We investigate the quantum dynamics of the electron spin resonance of topological defects (edge state) in dimerized chains. These objects are discontinuities of the spin chain protected by the properties of the global system leading to a quantum many-body multiplet protected from the environment decoherence. Despite recent achievements in the realization of isolated and finite spin chains, the potential implementation in quantum devices needs the knowledge of the relaxation and decoherence sources. Our study reveals that electron spin lattice relaxation is governed at lowest temperatures by phonon-bottlenecked process and at high temperature by the chain dimerization gap. We show that the inter edge-state effective dipolar field is reduced by the intrachain exchange coupling leading to a longer coherence time than isolated ions at equivalent concentration. Ultimately, we demonstrate that the homogeneous broadening is governed by the intra-chain dipolar field, and we establish design principles for optimizing coherence in future materials.