Observation of type-III corner states induced by long-range interactions

TL;DR

This paper explores how long-range interactions influence higher-order topological phases in a kagome circuit, revealing a new type-III corner state and tunable Dirac semimetal features through experimental measurements.

Contribution

It demonstrates the emergence of a novel type-III corner state induced by long-range interactions in a topological circuit, expanding understanding of LRI effects on topological phases.

Findings

Discovery of a type-III corner state splitting from edge states

Observation of tunable Dirac cone features depending on LRI strength

Identification of four distinct topological phases in the system

Abstract

Long-range interactions (LRIs) are ubiquitous in nature. Higher-order topological (HOT) insulator represents a new phase of matter. A critical issue is how LRI dictates the HOT phases. In this work, we discover four topologically distinct phases, i.e., HOT phase, the bound state in the continuum, Dirac semimetal (DSM) phase, and trivial insulator phase in a breathing kagome circuit with tunable LRIs. We find an emerging type-III corner state in the HOT phase, which splits from the edge state continuum and originates from the strong couplings between nodes at different edges. We experimentally detect this novel state by impedance and voltage measurements. In the DSM phase, the Dirac cone exhibits an itinerant feature with a tunable position that depends on the LRI strength. Our findings provide a deeper understanding of the LRI effect on exotic topological states and pave the way for regulating interactions in topolectrical circuits.