Topologically protected elastic waves in phononic metamaterials

Abstract

Surface waves in topological states of quantum matter exhibit unique protection from backscattering induced by disorders, making them ideal carriers for both classical and quantum information. Topological matters for electrons and photons are largely limited by the range of bulk properties, and the associated performance trade-offs. In contrast, phononic metamaterials provide access to a much wider range of material properties. Here we demonstrate numerically a phononic topological metamaterial in an elastic-wave analogue of the quantum spin Hall effect. A dual-scale phononic crystal slab is used to support two effective spins for phonons over a broad bandwidth, and strong spin–orbit coupling is realized by breaking spatial mirror symmetry. By preserving the spin polarization with an external load or spatial symmetry, phononic edge states are shown to be robust against scattering from discrete defects as well as disorders in the continuum, demonstrating topological protection for phonons in both static and time-dependent regimes.

Nonlinear bifurcation diagrams of the current states of microcavity exciton-polaritons in the lattice

“…The modification and control of the dispersive properties are among the fundamental problems of current material science, photonics, condensed matter and solid state physics. In particular, manipulation of a band structure of a given physical system is a vital practical task of the design of new micro-and nanostructures possessing unusual properties [1]. Using of nonlinear properties of the medium for managing of its dispersion is one of the promising approaches for this task.…”

Geometric phase and topology of elastic oscillations and vibrations in model systems: Harmonic oscillator and superlattice

“…Phononic structures have also been shown recently to possess non-conventional topology as well as topologically constrained propagative properties. These properties have been achieved by breaking time-reversal symmetry through internal resonance or symmetry breaking structural features (e.g., chirality) [9][10][11][12][13][14][15][16][17][18][19] and without addition of energy from the outside. Energy can also be added to extrinsic topological elastic systems to break time reversal symmetry.…”

Topological Edge Floppy Modes in Disordered Fiber Networks

“…Introduction -Recent theoretical advances in applying concepts of topological states of matter to mechanical systems has led to the burgeoning new field of "topological mechanics", where nontrivial topologies of the phonon bands give rise to exotic mechanical and acoustic properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”