A new state of photonic matter: metamaterial continuous time crystal

Time crystals are an eagerly sought new phase of matter in which time-translation symmetry is broken. A time crystal, as originally proposed by Wilczek, is a quantum many-body system whose lowest-energy state is one in which the particles are in repetitive motion. Although it has been shown that such a system, breaking continuous time-translation symmetry by exhibiting oscillatory dynamics, is prohibited by nature, a number of systems which show discrete time-translation symmetry-breaking imposed by an external modulated parametric drive have been recently realized on various platforms, including trapped atomic ions, spin impurities, ultracold atoms, condensates of magnons and quantum computers. Recently, a quantum time crystal that breaks time-translation symmetry continuously has been observed in an atomic Bose-Einstein condensate inside an optical cavity. Continuous time crystals are also potentially of great interest in photonics as they can support a variety of new wave propagation phenomena. Here we report that a classical metamaterial nanostructure, a two-dimensional array of plasmonic metamolecules supported on flexible nanowires, can be driven to a state possessing all key features of a continuous time crystal: continuous coherent illumination by light resonant with the metamolecules’ plasmonic mode triggers a spontaneous phase transition to a superradiance alike state of transmissivity oscillations resulting from many-body interactions among the metamolecules, and which is characterized by long-range order in space and time.

Zheludev, Nikolai

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MacDonald, Kevin F.

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Ou, Jun-Yu

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Liu, Tongjun

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26 June 2023