The topological properties of an object, associated with an integer called the topological
invariant, are global features that cannot change continuously but only through abrupt …

The study of classical wave physics has been reinvigorated by incorporating the concept of
the geometric phase, which has its roots in optics, and topological notions that were …

The concept of topological energy bands and their manifestations have been demonstrated
in condensed matter systems as a fantastic paradigm toward unprecedented physical …

Phononic crystals (PnCs) control the transport of sound and heat similar to the control of
electric currents by semiconductors and metals or light by photonic crystals. Basic and …

Recently, we witnessed a tremendous effort to conquer the realm of acoustics as a possible
playground to test with topologically protected sound wave propagation. In this article, we …

Topologically gapless edge states, characterized by topological invariants and Berry's
phases of bulk energy bands, provide amazing techniques to robustly control the …

Realizing directional acoustic signal transmittance and reception robust against surrounding
noise and competing signals is crucial in many areas such as communication, navigation …

Second-order topological insulators, which exhibit capability of hosting topologically
protected zero-dimensional corner states distinct from the well-studied topological edge …

Topological insulators, originated in quantum systems, are recently generalized to
electromagnetic, acoustic, and elastic wave fields due to interesting wave controlling …

Valley interface states, resulting in acoustic valley Hall topological insulators, have recently
become a hot topic in the study of acoustic systems. On the basis of structural diversity and …