  Exceptional point degeneracies (EPD) of linear non-Hermitian systems have
been recently utilized for hypersensitive sensing. This proposal exploits the
sublinear response that the degenerate frequencies experience once the system
is externally perturbed. The enhanced sensitivity, however, might be offset by
excess (fundamental and/or technical) noise. Here, we developed a
self-oscillating nonlinear platform that supports transitions between two
distinct neuromorphic functionalities -- one having a spatially symmetric
steady-state, and the other with an asymmetric steady-state -- and displays
nonlinear EPDs (NLEPDs) that can be employed for noise-resilient sensing. The
experimental setup incorporates a nonlinear electronic dimer with
voltage-sensitive coupling and demonstrates two-orders signal-to-noise
enhancement of voltage variation measurements near NLEPDs. Our results resolve
a long-standing debate on the efficacy of EPD-sensing in active systems above
self-oscillating threshold.
