2017/08/31 by Stefan Imhof, Christian Berger, Florian Bayer +9 · 5 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Boundary (topology) #Chemical and Physical Properties of Materials #Gapless playback #Homogeneous space #Quantum #Realization (probability) #Topological Materials and Phenomena #Topological insulator #Topology (electrical circuits) #cond-mat.mes-hall
paper · pdf · doi:10.1038/s41567-018-0246-1
published as Nature Physics 14, 925-929 (2018) · 12 pages, 7 figures
openalex created_date 2017/08/31 · openalex publication_date 2018/08/28 · arxiv created 2019/06/29 · arxiv updated 2019/11/13 · openalex updated_date 2026/08/05
Quantized electric quadrupole insulators have recently been proposed as novel quantum states of matter in two spatial dimensions. Gapped otherwise, they can feature zero-dimensional topological corner mid-gap states protected by the bulk spectral gap, reflection symmetries and a spectral symmetry. Here we introduce a topolectrical circuit design for realizing such corner modes experimentally and report measurements in which the modes appear as topological boundary resonances in the corner impedance profile of the circuit. Whereas the quantized bulk quadrupole moment of an electronic crystal does not have a direct analogue in the classical topolectrical-circuit framework, the corner modes inherit the identical form from the quantum case. Due to the flexibility and tunability of electrical circuits, they are an ideal platform for studying the reflection symmetry-protected character of corner modes in detail. Our work therefore establishes an instance where topolectrical circuitry is employed to bridge the gap between quantum theoretical modelling and the experimental realization of topological band structures.