Coherent perfect absorption at an exceptional point

Absorbingly exceptional Most oscillating systems have a resonance or multiple resonances at which they ring out and are most sensitive to excitation. In non-Hermitian systems, open systems with gain and loss, the resonances have been found to coalesce into an exceptional point when the gain and loss can be engineered. Complementing these resonant exceptional points, Wang et al . show that controlling the absorption of a coupled microresonator system can produce a new kind of absorbing exceptional point. They also show how these exceptional points are distinct and how systems can be engineered to exhibit new scattering behavior. —ISO