Parity‐Time‐Symmetric Bimorphic Topological Insulators

Abstract

ABSTRACT We propose and experimentally realize a parity‐time ()‐symmetric bimorphic topological insulator, characterized by the coexistence of first‐ and second‐order topological phases. Our platform utilizes an anomalous Floquet model implemented in a 2D optical waveguide array, where symmetry is maintained via a four‐step driving protocol with spatiotemporally engineered loss. Despite the presence of dissipation, we demonstrate that the symmetry ensures a purely real quasienergy spectrum across the topological regime, effectively stabilizing boundary modes against the dynamical instabilities and mode competition typical of non‐Hermitian systems. Experimentally, we provide unambiguous evidence of this non‐Hermitian bimorphic phase by observing unidirectional, clockwise edge transport in the zero gap and robust corner localization in the gap. Our findings pave the way for further exploration of ‐symmetric and non‐Hermitian topological phases in nonlinear and many‐body regimes and provide novel insights into the realization of topological insulators in open quantum systems.