# A novel artificial condensed matter lattice and a new platform for one-dimensional topological phases

## TL;DR

This paper introduces a new artificial quantum lattice built from layered topological and trivial insulators, enabling the study and control of one-dimensional topological phases through engineered band structures.

## Contribution

The authors present a novel multilayer heterostructure that forms an emergent atomic chain with controllable topological properties, demonstrating a new platform for topological phase engineering.

## Key findings

- Demonstrated hybridization of interface states across layers
- Realized both topological and trivial phases in the superlattice
- Controlled electron hopping by changing heterostructure composition

## Abstract

Engineered lattices in condensed matter physics, such as cold atom optical lattices or photonic crystals, can have fundamentally different properties from naturally-occurring electronic crystals. Here, we report a novel type of artificial quantum matter lattice. Our lattice is a multilayer heterostructure built from alternating thin films of topological and trivial insulators. Each interface within the heterostructure hosts a set of topologically-protected interface states, and by making the layers sufficiently thin, we demonstrate for the first time a hybridization of interface states across layers. In this way, our heterostructure forms an emergent atomic chain, where the interfaces act as lattice sites and the interface states act as atomic orbitals, as seen from our measurements by angle-resolved photoemission spectroscopy (ARPES). By changing the composition of the heterostructure, we can directly control hopping between lattice sites. We realize a topological and a trivial phase in our superlattice band structure. We argue that the superlattice may be characterized in a significant way by a one-dimensional topological invariant, closely related to the invariant of the Su-Schrieffer-Heeger model. Our topological insulator heterostructure demonstrates a novel experimental platform where we can engineer band structures by directly controlling how electrons hop between lattice sites.