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

Structured waves are ubiquitous for all areas of wave physics, both classical and quantum,
where the wavefields are inhomogeneous and cannot be approximated by a single plane …

Recently, spatiotemporal optical vortex pulses carrying a purely transverse intrinsic orbital
angular momentum were generated experimentally [Optica 6, 1547 (2019) OPTIC8 2334 …

Chirality or handedness distinguishes an object from its mirror images, such as the spread
thumb, index finger, and middle finger of the right and left hand. In mathematics, it is …

Polarization singularities and topological polarization structures are generic features of
inhomogeneous vector wave fields of any nature. However, their experimental studies …

Wave fields with orbital angular momentum (OAM) have been widely investigated in
metasurfaces. By engineering acoustic metasurfaces with phase gradient elements, phase …

Topological phases of matter are classified based on their Hermitian Hamiltonians, whose
real-valued dispersions together with orthogonal eigenstates form nontrivial topology. In the …

It is well known that the spin angular momentum of light, and therefore that of photons, is
directly related to their circular polarization. Naturally, for totally unpolarized light …

Despite a long history of studies, acoustic waves are generally regarded as spinless scalar
waves, until recent research revealed their rich structures. Here, we report the experimental …