Progress in Topological Mechanics

Abstract

Topological mechanics is rapidly emerging as an attractive field of research where mechanical waveguides can be designed and controlled via topological methods. With the development of topological phases of matter, recent advances have shown that topological states have been realized in the elastic media exploiting analogue quantum Hall effect, analogue quantum spin Hall effect, analogue quantum valley Hall effect, higher-order topological physics, topological pump, topological lattice defects and so on. This review aims to introduce the experimental and theoretical achievements with defect-immune protected elastic waves in mechanical systems based on the abovementioned methods, respectively. From these discussions, we predict the possible perspective of topological mechanics.

Coexistence of Chiral and Antichiral Edge States in Photonic Crystals

“…[ 58,59 ] Although presented in photonics, these results can be readily adapted to other systems including sonics and mechanics. [ 60–63 ] Our study may pave the way for constructing novel topological interface transport, with promising reconfigurable on‐chip applications for classical (quantum) information processing and photonic computing.…”

Uncovering and Experimental Realization of Multimodal 3D Topological Metamaterials for Low‐Frequency and Multiband Elastic Wave Control

“…These so-called topological metamaterials enable low-loss transport and arbitrary directional manipulation of elastic waves via localized topological states that are protected from unwanted scattering in the presence of structural defects or disorder. [5][6][7][8][9] The remarkable capabilities and robustness of topological metamaterials have been exploited to enhance performance in technical applications that include vibration energy harvesters [10][11][12][13][14] and a mechanical information processor, [15] and have additionally inspired investigations on their potential implementation in on-chip devices [16][17][18][19] and elastic antennas. [20] Initial research concerning topological metamaterials focused on the theoretical prediction and experimental demonstration of 0D topological states in 1D mechanical structures (e.g., the wave is localized at a point in a rod) and 1D topological states in 2D mechanical structures (e.g., the wave is localized along a line waveguide in a thin plate).…”

“…These so‐called topological metamaterials enable low‐loss transport and arbitrary directional manipulation of elastic waves via localized topological states that are protected from unwanted scattering in the presence of structural defects or disorder. [ 5 , 6 , 7 , 8 , 9 ] The remarkable capabilities and robustness of topological metamaterials have been exploited to enhance performance in technical applications that include vibration energy harvesters [ 10 , 11 , 12 , 13 , 14 ] and a mechanical information processor, [ 15 ] and have additionally inspired investigations on their potential implementation in on‐chip devices [ 16 , 17 , 18 , 19 ] and elastic antennas. [ 20 ]…”

Subwavelength Chiral Spiral Acoustic Metamaterials for a Robust Topological Acoustic Insulator

“…The edge state characterized by the one-way transmission without backscattering lays a new pathway for acoustic wave guiding, which enables the acoustic wave to propagate robustly along the surface or edge being immune to the defects. By emulating the quantum Hall effect (QHE) [3,4], quantum spin Hall effect (QSHE) [5,6], and quantum Valley Hall effect (QVHE) [7,8] in electronic systems, similar topological transmission is also realized in classical acoustic systems [9][10][11][12][13][14][15]. The researchers [16][17][18] introduced the circulating fluid into the ring resonator, mimicking the magnetic field in an electronic system, and realized the analogue QHE.…”