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Time Crystals: Eternal Ticking Clocks Made of Atoms ⚡ экспресс

Original: "Time crystals in cavity-BEC systems"
· Jayson G. Cosme, Ludwig Mathey
arXiv:2605.23881 · 2026-05-22 · CC BY · ⏱ 1 min · Quantum Gases Quantum Physics
Physicists created three types of time crystals and learned to distinguish them.
Abstract

Scientists have studied special states of matter — time crystals, which, like an eternal pendulum, repeat motion in time all by themselves without any external push. In an experiment with ultracold atoms and light, they managed to identify three different types of these 'crystals.' What other hidden rhythms does matter hold?

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A time crystal resembles an eternal clock: its atoms spontaneously perform rhythmic movements. In ordinary clocks, a pendulum is driven by a spring or battery, but here the motion arises without an energy supply—the system simply returns to its initial state at regular intervals. This idea was proposed by Frank Wilczek in 2012. While in a spatial crystal atoms are frozen in a regular lattice, here it’s not the position that repeats in time, but the pattern of motion.

An ordinary crystal is a spatial pattern that repeats in different directions. A time crystal repeats its pattern in time, like the ticking of a metronome that doesn’t need winding.

In the experiment, scientists placed a cloud of atoms, cooled to ultralow temperatures, between two mirrors. Under these conditions, the atoms merge into a single quantum object, like one huge particle. Light trapped in the mirror cavity interacted with this cloud, and it spontaneously began to 'tick'—alternately contracting and expanding. The researchers detected photons escaping from the trap and, using photometry and spectroscopy, determined the rhythm of oscillations. Each type of time crystal had its own characteristic light signature—as if different clocks keep time in their own way. Although this resembles a perpetual motion machine, the crystal doesn’t violate physical laws: it doesn’t generate energy but simply exists in an unchanging pulsing state.

Because photons fly out of the trap at the speed of light, we can measure the state of the time crystal very quickly and without destroying it.

🎯 Theorists described time crystals in 2012, but the scientific community initially rejected the idea, thinking it violated the laws of thermodynamics.

🎬 The idea of structures living in time cycles echoes the plot of the movie 'Groundhog Day'—only here it’s not a day that repeats, but a quantum state.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterAlbert Einstein
Tags
photometry spectroscopy speed of light
Laws
Doppler effectprinciple of constancy of the speed of lightmass–energy equivalenceMaxwell's equationsPlanck's lawLorentz transformations
Original: arXiv:2605.23881 · CC BY · bridge42worlds