“…Superconducting metamaterials, resulting either from bare replacement of the metallic parts employed in conventional metamaterials by superconducting ones [37,12,11,38,39,40,41,42], or by constructing hybrid structures comprising superconducting components [43,44,45,46,47,48,14,49], or even by incoprorating the Josephson effect as in arrays of SQUIDs [50,18,19,32,24], have been already proposed and/or demonstrated experimentally. Their operation frequency spans a huge range, from zero [51,52,53,54] to microwaves [55,18,56,19,32] and to Terahertz [11,12,37,57,38,39,40,15,58,59,41,42] and visible [45] frequencies.…”