title: 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.
authors.affiliation: Microelectronics Research Centre, Electrical and Computer Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, Texas 78758, USA.
authors.forename: S Hossein
authors.initials: SH
authors.lastname: Mousavi
authors.affiliation: Department of Physics, Queens College of The City University of New York, Queens, New York 11367, USA.|The Graduate Centre of The City University of New York, New York, New York 10016, USA.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Khanikaev
authors.affiliation: Microelectronics Research Centre, Electrical and Computer Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, Texas 78758, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang