Topological States in Dimerized Quantum-Dot Chains Created by Atom Manipulation

Abstract

Topological electronic phases exist in a variety of naturally occurring materials but can also be created artificially. We used a cryogenic scanning tunneling microscope to create dimerized chains of identical quantum dots on a semiconductor surface and to demonstrate that these chains give rise to one-dimensional topological phases. The dots were assembled from charged adatoms, creating a confining potential with single-atom precision acting on electrons in surface states of the semiconductor. Quantum coupling between the dots leads to electronic states localized at the ends of the chains, as well as at deliberately created internal domain walls, in agreement with the predictions of the Su-Schrieffer-Heeger model. Scanning tunneling spectroscopy also reveals deviations from this well-established model manifested in an asymmetric level spectrum and energy shifts of the boundary states. The deviations arise because the dots are charged and hence lead to an onsite potential that varies along the chain. We show that this variation can be mitigated by electrostatic gating using auxiliary charged adatoms, enabling fine-tuning of the boundary states and control of their quantum superposition. The experimental data, which are complemented by theoretical modeling of the potential and the resulting eigenstates, reveal the important role of electrostatics in these engineered quantum structures.

arXiv comment16 pages double-line text plus appendix, 7 figures

References in corpus (14)

• Topological Insulators
• Topological Band Engineering of Graphene Nanoribbons
• Engineering of robust topological quantum phases in graphene nanoribbons
• Artificial flat band systems: from lattice models to experiments
• Novel Topological Phase with Zero Berry Curvature
• Topological states in engineered atomic lattices
• Robust zero-energy modes in an electronic higher-order topological insulator: the dimerized Kagome lattice
• Exotic electronic states in the world of flat bands: from theory to material
• Tailoring topological order and π-conjugation to engineer quasi-metallic polymers
• Designer quantum states of matter created atom-by-atom
• Gating a single-molecule transistor with individual atoms
• Poor man's topological quantum gate based on the Su-Schrieffer-Heeger model
• Tuneable topological domain wall states in engineered atomic chains
• Edge-dependent topology in Kekulé lattices

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• Quantum dots on the InAs(110) cleavage surface created by atom manipulation
• Topological boundary states in engineered quantum-dot molecules on the InAs(111)A surface
• Shot noise signatures identifying non-Abelian properties of Jackiw-Rebbi zero modes
• Charge waves and dynamical signatures of topological phases in Su-Schrieffer-Heeger chains