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, et al. “Robust localized zero-energy modes from locally embedded PT-symmetric defects.” Physical Review Research, vol. 2, no. 3, American Physical Society, Sept. 2020, p. 032057, doi:10.1103/PhysRevResearch.2.032057.
Physical Review Research