Optimal control of electromagnetic field using metallic nanoclusters
  The dielectric properties of metallic nanoclusters in the presence of an applied electromagnetic field are investigated using non-local linear response theory. In the quantum limit we find a non-trivial dependence of the induced field and charge distribution on the spatial separation between the clusters and on the frequency of the driving field. Using a genetic algorithm, these quantum functionalities are exploited to custom-design sub-wavelength lenses with a frequency controlled switching capability. 
Ilya Grigorenko, Stephan Haas, Alexander Balatsky, A.F.J. Levi