Physicists Made a Time Crystal We Can Actually See

Of all the eccentricities of the quantum realm, time crystals—atomic arrangements that repeat certain motions over time—might be some of the weirdest. But they certainly exist, and to provide more solid proof, physicists have finally created a time crystal we can actually see.

In a recent Nature Materials paper, physicists at the University of Colorado Boulder presented a new time crystal design: a glass cell filled with liquid crystals—rod-shaped molecules stuck in strange limbo between solid and liquid. It’s the same stuff found in smartphone LCD screens. When hit with light, the crystals jiggle and dance in repeating patterns that the researchers say resemble “psychedelic tiger stripes.”

“They can be observed directly under a microscope and even, under special conditions, by the naked eye,” said Hanqing Zhao, study lead author and a graduate student at the University of Colorado Boulder, in a release. Technically, these crystalline dances can last for hours, like an “eternally spinning clock,” the researchers added.

An asymmetrical curiosity

Time crystals first appeared in a 2012 paper by Nobel laureate Frank Wilczek, who pitched an idea for an impossible crystal that breaks several rules of symmetry in physics. Specifically, a time crystal breaks symmetry because its atoms do not lock into a continuous lattice, and their positions change over time.

Physicists have since demonstrated versions of Wilczek’s proposal, but these crystals lasted for a terribly short time and were microscopic. Zhao and Ivan Smalyukh, the study’s senior author and a physicist at the University of Colorado Boulder, wanted to see if they could overcome these limitations.

Finding the molecular ‘kink’

For the new time crystal, the duo exploited the molecules’ “kinks”—their tendency to cluster together when squeezed in a certain way. Once together, these kinks behave like whole atoms, the researchers explained.

“You have these twists, and you can’t easily remove them,” Smalyukh said. “They behave like particles and start interacting with each other.”

The team coated two glass cells with dye molecules, sandwiching a liquid crystal solution between the layers. When they flashed the setup with polarized light, the dye molecules churned inside the glass, squeezing the liquid crystal. This formed thousands of new kinks inside the crystal, the researchers explained.

“That’s the beauty of this time crystal,” said Smalyukh. “You just create some conditions that aren’t that special. You shine a light, and the whole thing happens.”

The team believes its iteration of the time crystal could have practical uses. For instance, a “time watermark” printed on bills could be used to identify counterfeits. Also, stacked layers could serve as a tiny data center.

It’s rare for quantum systems to be visible to the naked eye. Only time will tell if this time crystal amounts to anything—the researchers “don’t want to put a limit on the applications right now”—but even if it doesn’t, it’s still a neat demonstration of how physical theories exist in strange, unexpected corners of reality.