Photonic metamaterial analogue of a continuous time crystal

Time crystals are an eagerly sought phase of matter with broken time-translation symmetry. Quantum time discretely symmetry have been demonstrated in trapped ions, atoms and spins while continuously has observed atomic condensate inside optical cavity. Here we report that a classical metamaterial nanostructure, two-dimensional array plasmonic metamolecules supported on flexible nanowires, can be driven to state possessing all the key features continuous crystal: coherent illumination by light resonant metamolecules' mode triggers spontaneous transition superradiant-like transmissivity oscillations, resulting from many-body interactions among metamolecules, characterized long-range order space time. The phenomenon is interest study dynamic states strongly correlated regime applications all-optical modulation, frequency conversion timing.