Extended state reshaping in non-Hermitian topolectrical circuits

Topological modes in the bandgap are generally localized at the boundaries. However, recent research proposes a new topological mode arising from the non-Hermitian skin effect, whose energy can extend to the bulk, forming the topological extended state. Such a topological mode can increase the space utilization of topological devices, which is worth further exploration and confirmation in classical systems. Here, we propose a topological extended state reshaping in non-Hermitian topolectrical circuits with a skin effect, where the stairlike extended mode is reshaped by controlling the odd-even properties of unit cells in the electric circuit ring. The extended state reshaping is confirmed by measuring the stairlike voltage distribution in the experiment. Our finding enriches the characteristics of extended states, and has potential application in multichannel tunable topological devices based on the stairlike extended mode.