An intrinsic topological model in the absence of symmetry

Abstract

We study the vibrational spectrum of a constrained classical ring. Due to the presence of 2-order exceptional points, a topologically trivial band at the infinity can make the vibrational band topologically nontrivial. The symmetry, which is believed to be indispensable in topological models, is absent in this model. The fractional boundary states can be found in such classical system. Furthermore, the other aspect of the bulk boundary correspondence is revealed: an extra fractional exceptional point is topologically protected in bulk by the boundary states.