Realizing a symmetry protected topological phase through dimerized interactions

TL;DR

This paper demonstrates that in a one-dimensional system of spinless fermions, a symmetry protected topological phase can emerge solely through interactions, characterized by edge states, Berry phase, and string order, with observable experimental signatures.

Contribution

It reveals a new interaction-driven topological phase in 1D spinless fermions with dimerized interactions, distinct from non-interacting gapless states, and details the phase transition mechanisms.

Findings

Topological phase emerges only through interactions.

Dimerized interactions induce two degenerate bond-order phases.

Topological phase transition occurs via gap closing between bond-order phases.

Abstract

We show that in a system of one dimensional spinless fermions a topological phase and phase transition can emerge only through interaction. By allowing a dimerized or bond-alternating nearest neighbour interaction we show that the system exhibits a symmetry protected topological phase while its non-interacting limit is a gapless state. The non-trivial topological character appears due to the onset of two degenerate bond-order phases as a function of dimerized interaction which are found to be topologically distinct from each other. As a result a topological phase transition occurs between these bond order phases through a gap closing point. However, in the limit of strong interaction, the bond order phases are connected through a gapped charge density wave phase possessing local antiferromagnetic order. The topological nature is characterized by the edge states, Berry phase and non-local string order parameter. At the end we provide possible experimental signatures of the emergent symmetry protected topological phase transition in terms of Thouless charge pumping and density-density correlation.