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Kyungmin Lee, Minwook Kyung, Jagang Park, Yung Kim, Hyuckjoon Cho, Joonhee Choi, and Bumki Min

Department of Mechanical Engineering

Demonstration of a microwave anharmonic time crystal

A discrete time translational symmetry (DTS) can be spontaneously broken in periodically-driven classical and quantum systems. The DTS breaking was first observed in periodically-driven quantum spin systems where a many body localization (MBL), in principle, prevents the system from heating to an infinite temperature. Since then, several classical systems such as those describable with a cellular automaton and a Frenkel–Kontorova model have been proposed as a potential discrete time crystal, but their realizability has not been fully verified yet. Here, we experimentally demonstrate the existence of two distinct nonequilibrium time crystalline phases in a microwave Floquet lattice consisting of a coupled array of periodically-driven nonlinear LC resonators. Interestingly, it turns out that the nonlinearity inherent in the proposed platform plays two key roles; a mimicry of classical many-body system and a prevention of heating and melting. Specifically, we observe a discrete time crystalline phase as well as an anharmonic one exhibiting commensurate and incommensurate responses with respect to the period of driving. We further confirmed the rigidity of these two phases against spatial and temporal disturbance.

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