A time crystal sounds like something from some high-concept science-fiction, but they're very real – and as new research reveals, you might have some in your home already. Scientists from Yale University have now spotted the signature of a time crystal in a common crystal that crops up in off-the-shelf crystal-growing kits for kids.

Crystals are characterized by a repeating pattern of atoms. In a regular crystal, the atoms repeat across space, forming a lattice structure. But in 2012, an MIT professor proposed the idea of a time crystal, whose atoms repeat across time instead. That means that their atomic spins flip back and forth in a kind of "ticking" motion that's locked to a certain frequency.

The strange thing is, this rhythm begins to fall out of step with the force that kicks it off, creating a system eerily like perpetual motion. The existence of time crystals was confirmed in 2016, when a UC Berkeley team created them for the first time in a lab experiment.

That inspired the Yale researchers to begin looking for the unique signatures of time crystals in other solids. Their first port of call was a crop of monoammonium phosphate (MAP) crystals, which grow so readily that they're often used in crystal-growing kits for kids. The team thought that time crystals would only form in crystals with more disorder to their atoms, but after peering inside these MAP crystals using nuclear magnetic resonance, they quickly found the fingerprints they were looking for.

"Our crystal measurements looked quite striking right off the bat," says Sean Barrett, principal investigator on the research. "Our work suggests that the signature of a discrete time crystal (DTC) could be found, in principle, by looking in a children's crystal growing kit."

The team conducted what they call a "time crystal echo" experiment, and were able to probe the hidden quantum order within the system. Their strange find raises more questions though: time crystals were created under very specific conditions in the UC Berkeley lab, but just how they're able to form naturally remains a mystery.

"It's too early to tell what the resolution will be for the current theory of discrete time crystals, but people will be working on this question for at least the next few years," says Barrett.

The research was published in two papers, appearing in the journals Physical Review Letters and Physical Review B.

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