Hybrid Disclination Skin-topological Effects in Non-Hermitian Circuits

TL;DR

This paper introduces a non-Hermitian 2D SSH disclination model with skin-topological states, predicts disclination states and fractional charges in non-Hermitian lattices, and experimentally verifies these states in a circuit platform, extending bulk-disclination correspondence.

Contribution

It develops a non-Hermitian disclination model with skin-topological states, predicts novel disclination phenomena, and demonstrates experimental observation in circuits, expanding the understanding of topological effects in non-Hermitian systems.

Findings

Prediction of disclination states in non-Hermitian lattices

Experimental observation of skin-topological disclination states

Extension of bulk-disclination correspondence to non-Hermitian systems

Abstract

The bulk-disclination correspondence (BDC) is a fundamental concept in Hermitian systems that has been widely applied to predict disclination states. Recently, disclination states have also been observed and experimentally verified in non-Hermitian systems with C6 lattice symmetry, where gain and loss are introduced to induce non-Hermiticity. In this Letter, we propose a non-Hermitian two-dimensional (2D) Su-Schrieffer-Heeger (SSH) disclination model with skin-topological (ST) disclination states, and calculate its biorthogonal Zak phase. Together with the real-space disclination index, we predict the emergence of disclination states in a C4-symmetric non-Hermitian lattice and the corresponding fractional charge. We also generalize the symmetry indicator within the biorthogonal framework to predict the anomalous filling near the disclination core. Experimentally, the model is implemented on a nonreciprocal circuit platform, where we analyze the impedance matrix characterized by complex eigenfrequencies and directly observe the ST disclination states. Our work further extends the bulk-disclination correspondence to the non-Hermitian realm.