Topological disclination states and charge fractionalization in a non-Hermitian lattice

TL;DR

This paper demonstrates that non-Hermitian lattices with disclinations can host unique topological states induced by gain and loss, leading to observable shifts in optical emission properties.

Contribution

It introduces a novel non-Hermitian topological phase with disclination states arising from charge fractionalization, analyzed via biorthogonal Wilson loops.

Findings

Disclination states are induced by gain/loss and do not exist in Hermitian limit.

Charge fractionalization underpins the topological states.

Experimental signatures include abrupt shifts in emission intensity and frequency.

Abstract

We show that a non-Hermitian lattice with a disclination can host topological disclination states that are induced by on-site gain and loss. The disclination states are inherently non-Hermitian as they do not exist in the limit of zero gain/loss. They arise from charge fractionalization in the non-Hermitian lattice, which we establish using non-Hermitian Wilson loops calculated with biorthogonal products. The model can be realized using an array of optical resonators, with the emergence of the topological disclination states manifesting as an abrupt shift in emission intensity and frequency upon tuning the gain/loss level.