Fractional Topological States in Quantum Spin Chains with Periodical Modulation

TL;DR

This paper demonstrates the existence of fractional topological states in one-dimensional periodically modulated quantum spin chains, revealing nontrivial ground states, edge states, and fractional statistics, expanding the understanding of correlated spin systems.

Contribution

It introduces fractional topological states in 1D quantum spin chains with periodic modulation, characterized by nonzero Chern numbers and edge states, a novel finding in correlated spin systems.

Findings

Existence of topologically nontrivial degenerate ground states

Identification of nonzero-integer total Chern numbers

Observation of fractional and non-Abelian statistics

Abstract

We report the findings of fractional topological states in one-dimensional periodically modulated quantum spin chains with up to third neighbor interactions. By exact numerical studies, we demonstrate the existence of topologically nontrivial degenerate ground states at some specific magnetizations, which can be characterized by the nonzero-integer total Chern numbers of the degenerate ground states and the emergence of nontrivial edge states under open boundary conditions. We find that the low-energy excitations obey bosonic $\nu=1/2$ fractional statistics for the spin-$1/2$ system and $\nu=1$ non-Abelian statistics for the spin-$1$ system, respectively. The discovered fractional quantum states provide another route to the theoretical exploration of fractional quantum states in correlated spin systems.