Synthetic Kramers Pair in Phononic Elastic Plates and Helical Edge States on a Dislocation Interface

Abstract

In conventional theories, topological band properties are intrinsic characteristics of the bulk material and do not depend on the choice of the reference frame. In this scenario, the principle of bulk‐edge correspondence can be used to predict the existence of edge states between topologically distinct materials. In this study, a 2D elastic phononic plate is proposed with a Kekulé‐distorted honeycomb pattern engraved on it. It is found that the pseudospin and the pseudospin‐dependent Chern numbers are not invariant properties, and the ℤ2 number is no longer a sufficient indicator to examine the existence of the edge state. The distinctive pseudospin texture and the pseudomagnetic field are also revealed. Finally, the synthetic helical edge states are successfully devised and experimentally implemented on a dislocation interface connecting two subdomains with bulk pattern identical up to a relative translation. The edge state is also imaged via laser vibrometry.

Systematic generation of Hamiltonian families with dualities

“…Similar notions of dualities were suggested in systems ranging from self-assembled systems [10] to quantum rotors [11]. Rich consequences arise when a duality is combined with other constraints such as symmetries or conservation laws, ranging from degeneracies in the band structure [12][13][14] and topological states [15,16] to symmetries in the phonon response [17] and constraints on the stiffness tensor of an elastic medium [18].…”

Tracking Valley Topology with Synthetic Weyl Paths

“…Last but not the least, our study provides a concrete example that unveils intricate high-dimension band topology through easily controllable low-dimension physical systems [62][63][64][65][66][67][68][69][70][71][72][73]. In fact, similar methodology can also be employed to construct synthetic WPs with larger charges, e.g., by introducing a modulation degree of freedom to Kekulé lattices [74][75][76][77][78].…”

Tailoring Structure‐Borne Sound through Bandgap Engineering in Phononic Crystals and Metamaterials: A Comprehensive Review

“…The objective was mainly to provide an experimental proof of topological manifestations in elastodynamics, which was facilitated by centimeter size structures that can be easily fabricated and characterized. [163,164,[257][258][259][260][261][262][263] Other designs were later proposed at the microscale for the purpose of topological elastic waveguiding at high frequency (from hundreds of megahertz to few gigahertz) for microsystem integration. [165,[264][265][266][267]497] In contrast to QHE, the QSHE opens a path to a class of topological insulators without breaking the TRS.…”

“…They also created a nontrivial interface between two topologically different lattices, which hosts helical edge waves (Figure 6c). Another method to design elastic Z2 topological insulator is to leverage modal hybridization, [260][261][262][263][264] which forms a double Dirac degeneracy in the band structure. This double Dirac degeneracy can be lifted so that pseudospin states become separated, opening up a topological BG (Figure 6d).…”

“…in the Brillouin zone. [271] This zone-folding mechanism provides a robust route for constructing Z2 topological insulators in elastic plates [260,[262][263][264][265] and SAW systems. [266] Recently, a 3D elastic metacrystal that obtained both QHE and QSHE topological phases was explored, [272] which showed simultaneously topological surface states and hinge states.…”