Fig. 2: Corner states on the circuit.
From: Realization of quasicrystalline quadrupole topological insulators in electrical circuits
a Spectra of the Laplacian J vs. the frequency that is normalized to the resonant frequency ω0. The isolated mode crossing in the gap corresponds to the topological corner states. b The experimental impedance distribution at the resonant frequency ω0 demonstrates the spatial localization of the corner states. c The experimental two-point impedances measured between the left-up corner/edge/bulk site and another bulk site. d The theoretical two-point impedances. Both the experimental and theoretical results demonstrate the spectral localization of the corner states.
