University of Colorado Boulder physicists have created a “time crystal” visible to the human eye.
Nobel laureate Frank Wilczek first proposed the concept of a time crystal in 2012.
While other crystals, like diamonds, are defined by a repeating lattice pattern in space, a time crystal has a similarly organized structure but in the dimension of time.
Its components wouldn’t sit still, but would move and transform in a never-ending cycle.
The material’s design could enable various new technologies, including anti-counterfeiting measures, 2D barcodes, and optical devices.
“They can be observed directly under a microscope and even, under special conditions, by the naked eye,” said Hanqing Zhao, lead author and a graduate student in the Department of Physics at CU Boulder.
Time crystal under the microscope
Although once believed to be impossible and a violation of a key law of thermodynamics, time crystals were first observed in a 2016 experiment.
A notable example occurred in 2021 when physicists used Google’s quantum computer to create a network of atoms that repeated their movements after being triggered by a laser.
This new creation is unique among them because it is the “world’s first” one to be visible to the human eye.
Zhao and his collaborator, Professor Ivan Smalyukh, used liquid crystals—the same materials found in phone displays—to achieve this feat.
The researchers filled glass cells with liquid crystals, which are rod-shaped molecules that exhibit solid and liquid properties.
Shining a specific light on the samples makes the liquid crystals move in repeating patterns.
When viewed under a microscope, the creation’s swirling patterns resemble “psychedelic tiger stripes” and dance in a continuous, repeating cycle.
“Everything is born out of nothing. All you do is shine a light, and this whole world of time crystals emerges,” said Smalyukh.
The researchers explained the mechanism behind the phenomenon.
When the molecules are squeezed, they bunch together to form “kinks.” These kinks can move around and, in the right conditions, behave just like atoms.
“They behave like particles and start interacting with each other,” Smalyukh noted.
Use in anti-counterfeiting measures
In this new study, researchers placed a liquid crystal solution between two pieces of glass coated with dye molecules.
While the sample was initially still, shining a specific light on it caused the dye molecules to change position.
Like dancers in a ballroom, these molecules break apart, spin, and come back together, over and over again.
This pattern was remarkably stable, remaining unbroken even when the temperature of the sample was changed.
“That’s the beauty of this time crystal,” Smalyukh said. “You just create some conditions that aren’t that special. You shine a light, and the whole thing happens.”
The researchers suggest that these materials could create advanced anti-counterfeiting measures.
For instance, embedding “time watermarks” in currency could allow a simple light to reveal a unique, moving pattern that would be almost impossible to copy.
Furthermore, the physicists suggest that time crystals could be stacked to create more complex patterns. This structure could be a new way to store large digital data.
As the technology is further developed and tested, the team believes it can be used in ways other than mentioned in the current study.
The findings were reported in the journal Nature Materials.