Hermitian and non-Hermitian Weyl physics in synthetic three-dimensional piezoelectric phononic beams

He, Liangshu; Li, Yan; Djafari‐Rouhani, Bahram; Jin, Yabin

doi:10.1103/physrevresearch.5.023020

Cited by 7 publications

(3 citation statements)

References 45 publications

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“…This phenomenon is also observed in the study of flexural waves within a piezoelectric metabeam. [ 305 ] Although the existence of a Weyl point does not necessitate PT symmetry, it is achieved by appropriately tuning gain and loss parameters. Indeed, the exploration of elastic wave manipulation in non‐Hermitian systems that do not necessarily adhere to PT symmetry has proven to be more fruitful, [ 37,300–304 ] including intelligent non‐Hermitian MM systems.…”

Section: Intelligent Parity‐time Symmetric Mmsmentioning

confidence: 99%

“…Indeed, the exploration of elastic wave manipulation in non‐Hermitian systems that do not necessarily adhere to PT symmetry has proven to be more fruitful, [ 37,300–304 ] including intelligent non‐Hermitian MM systems. [ 305–309 ] This is attributed to the absence of the requirement for strict balance between gain and loss in such systems. Although there have been some recent studies on non‐Hermitian elastic MMs with or without PT symmetry, how to realize experimental implementation and even intelligent manipulation is still worthy of further research.…”

Section: Intelligent Parity‐time Symmetric Mmsmentioning

confidence: 99%

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Wave Manipulation in Intelligent Metamaterials: Recent Progress and Prospects

Wu,

Jiang,

Jiang

et al. 2024

Adv Funct Materials

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Metamaterials (MMs), which include phononic crystals (PCs) as a particular type, exhibit anomalous wave propagation properties through artificial design of topologies or lattice forms of unit‐cells. Recent advancements in MMs signify an ascendant research trend, providing promising design ideas and means for unprecedented wave propagation properties. The imperative for on‐demand, real‐time active control of wave propagation underscores the significance of tunable manipulation of acoustic/elastic waves, promoting the design and development of tunable MMs. Furthermore, the versatility of intelligent materials and their ongoing development and innovation contribute significantly to the emergence of diverse intelligent MMs. This comprehensive survey provides an overview of recent advancements and current research trends in the interdisciplinary field of intelligent MMs with electro‐/magneto‐mechanical couplings. The primary objective of the review is to emphasize significant progress in agile manipulation of acoustic/elastic waves in electro‐/magneto‐mechanical coupled MMs, followed by an in‐depth exploration of intelligent metasurfaces, topological MMs, non‐Hermitian parity‐time symmetric wave systems, odd elastic MMs, and spatiotemporally modulated MMs. Special emphasis is given to multi‐field coupling effects. The review concludes with a summary and outlines potential prospects, offering a timely and informative guide for future studies on actively tunable PCs and MMs in practical engineering applications.

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Section: Intelligent Parity‐time Symmetric Mmsmentioning

confidence: 99%

Section: Intelligent Parity‐time Symmetric Mmsmentioning

confidence: 99%

Wave Manipulation in Intelligent Metamaterials: Recent Progress and Prospects

Wu,

Jiang,

Jiang

et al. 2024

Adv Funct Materials

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“…The first category involves the inclusion of non-Hermitian features in existing acoustic topological systems, which modifies the topological states in the presence of non-Hermiticity. For example, for an acoustic Weyl semimetal, the Weyl points will spread to Weyl exceptional rings in the presence of non-Hermiticity introduced by gain and loss [144,213]. Incorporating non-Hermiticity also modifies the bulk-boundary correspondence for topological insulators, leading to the so-called non-Hermitian skin effect (NHSE) which has been actively researched in the following areas of acoustics: (1) NHSE modifies the wave functions of TMs by adding directional responses, leading to chiral transportation [214] and directional amplification/decay of TMs [129,215]; (2) NHSE endows the topological edge modes with further spatial confinement, where directional transport owing to NHSEs results in wave accumulated at certain corners and hence forming a higher-order topological insulators supporting corner states [153,216,217] (figures 12(a) and (b)); (3) NHSE can modify the wave functions of TMs by delocalization, which leads to a topological state spreading in the bulk and hence is called the Extended State in a Localized Continuum [218]; (4) More generally, there is a competition between NHSEs and TMs, and thus NHSE can be used to arbitrarily morph the wavefunctions [154].…”

Section: Non-hermitian Acoustics In Topological Systemsmentioning

confidence: 99%

Non-local and non-Hermitian acoustic metasurfaces

Wang,

Dong,

et al. 2023

Rep. Prog. Phys.

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Acoustic metasurfaces are at the frontier of acoustic functional material research owing to their advanced capabilities of wave manipulation at an acoustically vanishing size. Despite significant progress in the last decade, conventional acoustic metasurfaces are still fundamentally limited by their underlying physics and design principles. First, conventional metasurfaces assume that unit cells are decoupled and therefore treat them individually during the design process. Owing to diffraction, however, the non-locality of the wave field could strongly affect the efficiency and even alter the behavior of acoustic metasurfaces. Additionally, conventional acoustic metasurfaces operate by modulating the phase and are typically treated as lossless systems. Due to the narrow regions in acoustic metasurfaces' subwavelength unit cells, however, losses are naturally present and could compromise the performance of acoustic metasurfaces. While the conventional wisdom is to minimize these effects, a counter-intuitive way of thinking has emerged, which is to harness the non-locality as well as loss for enhanced acoustic metasurface functionality. This has led to a new generation of acoustic metasurface design paradigm that is empowered by non-locality and non-Hermicity, providing new routes for controlling sound using the acoustic version of 2D materials.This review details the progress of non-local and non-Hermitian acoustic metasurfaces, providing an overview of the recent acoustic metasurface designs and discussing the critical role of non-locality and loss in acoustic metasurfaces. We further outline the synergy between non-locality and non-Hermiticity, and delineate the potential of using non-local and non-Hermitian acoustic metasurfaces as a new platform for investigating exceptional points (EPs), the hallmark of non-Hermitian physics. Finally, the current challenges and future outlook for this burgeoning field are discussed.

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