Orbital hybridization endowed topological insulators

Topological metamaterials have garnered extensive attention due to their defect/disorder immunity and extraordinary ability in wave manipulations. A very general scheme to realize the intriguing topological phenomena arises from the Su-Schrieffer-Heeger (SSH) lattices, the definition of the unit-cell within which is ambiguous, and the topological states are vulnerable to the profiles of boundary terminals in most prior scenarios. Here, we suggest a simple cylinder as the unit-cell hosting multiple reverse-parity orbitals to validate the acoustic single-atom topological insulators. We illustrate that the intrinsically orbital hybridization within the single-atom underpins the emergence of orbital edge states in the 1D array, regardless of boundary profiles, distinctly distinguished from the conventional SSH models in theory and simulation. We also analyze the topological features and phase transitions with energy bands. The orbital-hybridization edge modes and their boundary insensitivity are experimentally validated by several acoustic samples. Moreover, to elucidate the extendibility of this strategy, we experimentally unravel the distinct orbital hybridization corner modes and their multipolar topological nature as well as the robustness against irregular boundaries within a C3 symmetry undistorted Kagome lattice. Our findings deepen the understanding of complex interactions between multiple orbitals within a single atom and topology, shedding light on orbital-hybridization topological physics, information communication, and the miniaturization of devices.