Topologically Protected Phononic Wave Guides

By taking advantage of recent progress in the understanding of electrons in solids, we found a way to demonstrate the existence of topologically protected phononic surface states. In contrast to ordinary phononic states, the topologically protected counterparts are extremely robust against imperfections in the sustaining material. Based on our work, acoustic metamaterials are conceivable which can capitalize on the stability of the topological surface phonons as reliable wave guides. These offer robust transport channels for vibrational energy, making them ideal candidates for applications. Among them are acoustic lensing, as used in ultrasonic sensing, and an advanced way of acoustic insulation.