We demonstrate the creation of robust localized zero-energy states that are induced into topologically trivial systems by insertion of a PT-symmetric defect with local gain and loss. A pair of robust localized states induced by the defect turns into zero-energy modes when the gain-loss contrast exceeds a threshold, at which the defect states encounter an exceptional point. Our approach can be used to obtain robust lasing or perfectly absorbing modes in any part of the system.
Mostafavi, Fatemeh; Yuce, Cem; Magana-Loaiza, Omar S.; Schomerus, Henning; and Ramezani, Hamidrez, "Robust localized zero-energy modes from locally embedded PT-symmetric defects" (2020). Physics and Astronomy Faculty Publications and Presentations. 401.