Fig. 3: Mechanical Kitaev chain.
From: Strain topological metamaterials and revealing hidden topology in higher-order coordinates
a A mechanical monomer chain with transverse and rotational degrees of freedom maps to the Kitaev chain after fine-tuning. b Topological phase diagram of the Kitaev chain. The path of the fine-tuned mechanical chain follows the curved solid line (colorbar from yellow to black representing the value of the parameter P). Two cases experimentally tested herein (P = 1.5 and P = 2.5) are marked with triangles. c Dispersion diagrams for P = 1.5 and P = 2.5 are obtained in two ways: Analytically, via the lumped-mass model, and numerically, using the finite element method. H and s are the varying dimensions. Colorbar denotes modal dominance. d The winding number of \({\tilde{D}}_{u,{{{{{{{\rm{bulk}}}}}}}}}\) suggests a topologically non-trivial phase for P < 2. e Evolution of the spectrum of finite chain with an even number of particles (200) and fixed boundaries as we change P. Edge states emerge for P < 2. f Profiles of the edge states in e for P = 1.5. Due to particle-hole symmetry, the profiles of effective particles u and holes \(\Phi /\sqrt{P}\) are either identical or differ by phase.
