Enhanced Radio-Frequency Sensors Based on a Self-Dual Emitter-Absorber

We propose and experimentally demonstrate a parity-time-symmetric electronic system exhibiting the self-dual emitter-absorber property with remarkable modulation depth in radio-frequency (rf) region. The dramatically different rf responses between emitter absorber modes may allow detection of ultrasmall conductive or reactive perturbations. Our measurement results show that even perturbation on order ${10}^{\ensuremath{-}2}$ can greatly change system's output intensity by more than 30 dB, consistent theoretical prediction. measured sensitivity is far beyond traditional sensors based Fabry-Perot resonator, lead to monotonic high resolvability.