Kevin Chen's article Experimental observation of optical Weyl points and Fermi arc-like surface states, published in Nature Physics, was the subject of a "News and Views" article entitled Topological Photonics: Come to Light. The physics idea leading to this paper originated from Penn State collaborator Mikael Rechtsman.
Topological states of matter can exhibit a range of unique quantum phenomena that are of interest to various fields of classical physics, such as acoustics, mechanics or photonics. Although a number of these topological states have been successfully emulated in photonics, their application has been restricted to certain frequencies. Most topological properties have been demonstrated in two-dimensional (2D) systems; however, a variety of new topological properties have been predicted for three-dimensional (3D) systems. The study published in Nature Physics marks an important step by emulating Weyl points, which constitute the simplest possible topologically nontrivial band structure, in three dimensions.