Experimental realization of twofold topological phase transition induced by long-range hoppings in one-dimensional chains
Long-range hoppings offer a powerful mechanism to engineer exotic topological phases beyond conventional tight-binding models. Here, we experimentally demonstrate a twofold topological phase transition driven by third-nearest-neighbor couplings in a one-dimensional phononic chain that emulates cis-polyacetylene. Tunable hopping parameters in highly structured aluminum plates allow us to observe the emergence of Dirac points, a valley pseudospin structure, and topological edge states. The experimental results are supported by non-equilibrium Green's function transport calculations. Our findings confirm the predicted long-range phase diagram and establish phononic metamaterials as a versatile platform for exploring topological phenomena beyond the Su-Schrieffer-Heeger paradigm.