Exceptional points (EPs) are non-Hermitian singularities where two or more eigenstates coalesce, resulting in the eigenspace collapsing in dimensionality. Over the past decade, researchers have uncovered a wealth of exotic phenomena near EPs.

In laser physics, for example, EPs have been linked to pump-induced laser termination, loss-induced lasing, and the design of quasi-parity-time-symmetric laser systems that boost the output power of large-area lasers while preserving single-mode operation.