Scattering properties of parity-time symmetric nanoparticle dimers

We study the unusual scattering response of a parity-time (PT) symmetric pair of subwavelength nanoparticles with complex conjugate permittivities. The poles and zeros of the scattering cross section are analytically derived, showing intriguing properties. In the complex plane of the relative permittivity, we find interesting opportunities for scattering engineering, including conditions for extremely low or large scattering efficiencies that can be merged together to induce very sharp scattering features. Our results pave the way to a plethora of novel phenomena in nanophotonics based on balanced loss and gain.