Controlling Microwaves in Non-Hermitian Metamaterials

When designing a metamaterial, to obtain excellent resonance characteristics the dissipative loss of subcomponents usually should be minimized. However, this study takes the opposite approach and harnesses the dissipation. In such a non-Hermitian metamaterial, a bound state in the continuum (BIC) with an infinite $Q$-factor is observed, and an extremely steep transition from complete extinction to nearly perfect transmission is achieved in a narrow band. By repurposing dissipation as a coupling mechanism, non-Hermitian metamaterials open avenues for microwave sensing, switching, and the realization of slow microwave light.