Realization of the square-root higher-order topology in decorated Su–Schrieffer–Heeger electric circuits
Shengqun Guo, Pan Guangwu, Jinke Huang, Ruimin Huang, Fengjiang Zhuang, Shaojian Su, Zhili Lin, Weibin Qiu, Qiang Kan
Abstract
In this work, we experimentally implemented square-root higher-order topological insulators (HOTIs) in topological electric circuits with decorated Su–Schrieffer–Heeger (SSH) lattice. Due to the square-root operation, the corner states of the square-root HOTIs typically appear on the finite energy. Through theory and experiments, the corner states in both the parent and square-root HOTIs models, as well as their spectrum connection, were demonstrated. Our work not only experimentally substantiates the existence of square-root higher-order topology in decorated SSH lattice model, from the perspective of electric circuits, but also extends the possibilities for observing various topological phases in acoustic and mechanical systems.