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    Doesn’t an ordinary oscillator meet the definition of ‘time crystal’? Such as a pendulum, or those little clock devices used in electronics?

    Periodic movers such as those have a geometric structure if you lay time out as a spatial dimension.

    A pendulum would look roughly like a 2D ribbon with one edge taking the path of a sin wave (approximately? I’m no mathematician!) and the other edge being a straight line.

    Is that not the exact sort of structure that these ‘time crystals’ have?

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      My guess would be those are near time crystals as the pendulum doesn’t go to EXACTLY where it was, and not on an atomic scale. Typically crystals are crystals down to an atomic scale, this is what makes a tree not a crystal. I’m just guessing though.

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        I’m not 100% sure, but I think the key difference is intended to be that this is in the lowest energy state. i.e. if you leave it alone then it would just keep going - it won’t decay because it has no lower energy state to fall into. The pendulum has a lower energy state (not moving).

        How that can be reconciled with the fact that they are pulsing lasers at the entangled ions I don’t know.

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          I’m not 100% sure, but I think the key difference is intended to be that this is in the lowest energy state. i.e. if you leave it alone then it would just keep going - it won’t decay because it has no lower energy state to fall into. The pendulum has a lower energy state (not moving).

          I think when they reduced the laser they still got the previous amount of “motion”