Reentrant Defect Modes in a PT-Symmetric Circuit*

Systems obeying PT-symmetry are a special case in non-Hermitian physics where real eigenvalue spectra can still emerge. They usually exhibit a phase diagram with different regimes of symmetry conservation or spontaneous symmetry breaking in their eigenstates. We examine a localized zero-energy defect mode within a PT-symmetric hopping model that disappears and re-emerges at different PT phase transitions and present an exhaustive explanation for this phenomenon. Our theoretical findings are confirmed by eigenstate measurements for different gain/loss profiles in an electrical circuit implementation.