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 …

Within a time span of 15 years, acoustic metamaterials have emerged from academic
curiosity to become an active field driven by scientific discoveries and diverse application …

We report a new type of phononic crystals with topologically nontrivial band gaps for both
longitudinal and transverse polarizations, resulting in protected one-way elastic edge …

Metamaterials with a Dirac-like cone dispersion at the center of the Brillouin zone behave
like an isotropic and impedance-matched zero refractive index material at the Dirac-point …

Acoustics is a classical field of study that has witnessed tremendous developments over the
past 25 years. Driven by the novel acoustic effects underpinned by phononic crystals with …

By using the k⇀· p⇀ method, we propose a first-principles theory to study the linear
dispersions in phononic and photonic crystals. The theory reveals that only those linear …

Waves are generally characterized by angular frequency ω and wavevector k. Accordingly,
this tutorial is structured into two parts, one on resonance-based acoustic metamaterials, in …

We introduce the acoustic equivalent of “supercoupling” by studying the anomalous sound
transmission and uniform energy squeezing through ultranarrow acoustic channels filled …