# Robust zero-energy modes in an electronic higher-order topological insulator: the dimerized Kagome lattice

## TL;DR

This paper reports the experimental realization of a higher-order electronic topological insulator using a dimerized Kagome lattice created with CO molecules on a Cu surface, demonstrating corner states protected by symmetry.

## Contribution

It introduces a novel electronic HOTI realized through atom manipulation, showcasing corner modes in a dimerized Kagome lattice, advancing quantum simulation techniques.

## Key findings

- Corner states observed in the dimerized Kagome lattice.
- Topological states protected by generalized chiral symmetry.
- Robustness of corner modes against perturbations.

## Abstract

Quantum simulators are an essential tool for understanding complex quantum materials. Platforms based on ultracold atoms in optical lattices and photonic devices led the field so far, but electronic quantum simulators are proving to be equally relevant. Simulating topological states of matter is one of the holy grails in the field. Here, we experimentally realize a higher-order electronic topological insulator (HOTI). Specifically, we create a dimerized Kagome lattice by manipulating carbon-monoxide (CO) molecules on a Cu(111) surface using a scanning tunneling microscope (STM). We engineer alternating weak and strong bonds to show that a topological state emerges at the corner of the non-trivial configuration, while it is absent in the trivial one. Contrarily to conventional topological insulators (TIs), the topological state has two dimensions less than the bulk, denoting a HOTI. The corner mode is protected by a generalized chiral symmetry, which leads to a particular robustness against perturbations. Our versatile approach to quantum simulation with artificial lattices holds promises of revealing unexpected quantum phases of matter.