Optical PT-Symmetric Counterparts of Ordinary Metals

How one can fabricate the Parity-Time (PT) symmetric siblings of commonly used metals in the visible? This paper tries to give an answer to that question by providing the features of the active media, which conjugately pair the complex permittivities of the ordinary metals (Copper, Aluminum, Silver, Gold, Platinum) at the optical frequencies. The frequency response model of the quantum dots (QDs) is used to evaluate the effective permittivity of the active material; their characteristics which give a PT-symmetric counterpart for the considered metal are deduced through a multi-step optimization process. The required resonance frequencies, loss factors, and degrees of population inversion for the QDs are provided for various frequencies and metals. The response of the metals when they are PT-symmetrically coupled with the provided mixtures is demonstrated in specific photonic configurations and interesting properties with certain applicability potential are revealed.