Experimental observation of edge-dependent quantum pseudospin Hall effect

It is a conventional wisdom that the helical edge states of quantum spin Hall (QSH) insulator are particularly stable due to topological protection time-reversal symmetry. Here, we report first experimental observation an edge-dependent (pseudo-)spin effect by employing two Kekule electric circuits with molecule-zigzag and partially-bearded edges, where chirality circulating current in unit cell mimics electron spin. We observe helicity flipping in-gap modes emerging opposite parameter regions for geometries. Experimental findings interpreted terms mirror winding number defined cell, choice which exclusively depends on shape. Our work offers deeper understanding boundary QSH phase, pave way studying spin-dependent physics circuits.