Spatiotemporal Non-Hermitian Skin-Effect in a Fast-Gain Laser

Topological bound states offer robust and defect-immune confinement of energy, enabling precise control over light waves even in the presence of imperfections or disorder in the system. Initially studied only in Hermitian systems, Topological states were recently explored in non-Hermitian platforms [1], which through gain and loss engineering allow for robust states, topological skin-effect [2] and even topological lasing. Interestingly, such states result from models in space, while suggestions to study topology in time varying frames [3] are experimentally challenging, resulting only in artificial lattices mimicking the time dimension [4].