Exceptional Antimodes in Multi‐Drive Cavity Magnonics

ABSTRACT Driven‐dissipative systems provide a natural setting for the emergence of exceptional points—i.e. non‐Hermitian degeneracies where eigenmodes coalesce. These points are important for applications such as sensing, where enhanced sensitivity is desired, and exhibit interesting and useful phenomena that can be controlled with experimentally accessible parameters. In this regard a four‐port, three‐mode, cavity‐magnonics platform is demonstrated in which two microwave excitations can be precisely phase shifted and/or attenuated relative to one another. We show that destructive interference between the hybridized cavity‐magnon modes give rise to antimodes (antiresonances) in the transmission spectrum, enabling CPE of the outgoing signals at selected ports. For any given system parameters, the microwave excitations can be used to actively tune the system to antimode exceptional points, without the fine tuning conventionally required to obtain exceptional points. Such controllable, interference‐based engineering of exceptional points provides a practical and flexible pathway toward next‐generation, high‐sensitivity sensing devices operating at microwave frequencies.