Higher-order exceptional points in non-Hermitian systems enable extraordinarily sensitive detection, but require complex nonlinear gain. The authors show that frequency-dependent gain from simple impedance observers achieves a third-order exceptional point in a parity-time-symmetric dimer and a fifth-order exceptional point in an anti-parity-time-symmetric trimer, offering a practical route to enhanced sensing without nonlinear complications
- Xuanhao Zhang
- Ziyi Zhu
- Yuhua Cheng