All crystals are formed from atoms arranged in a repeating pattern. The difference between time crystals and ordinary crystals, such as salt or quartz, is that the latter can only exist in the three dimensions of space, while the first has atoms repeating in the fourth dimension as well.
First theorized in 2012 and identified as a new form of matter in 2016, time crystals have so far only been created in the lab, reports Popular Mechanics.
And yet, for the first time ever, scientists at Yale University in Connecticut have spotted the signature of a discrete time crystal (DTC) in what is generally deemed as a children's toy.
According to a university news release, Yale physicists have published two separate studies describing what is the second known experiment that observed a telltale signature for a DTC in a solid.
The solid in question refers to monoammonium phosphate (MAP) crystals, which are so easy to grow that they are often included in crystal growing kits for children.
The two studies, one published in the Physical Review Letters and the other in Physical Review B, argue that time crystals can form in all kinds of other situations that don't necessarily pertain to the lab environment. In fact, the Yale physicists suggest that time crystals may be easier to create than previously believed.If anything, their studies provide scientists with new puzzles to solve over the next few years, as the scientific community will undoubtedly try to get to the bottom of how time crystals are formed, says Yale physics professor Sean Barrett, principal investigator for both papers.
"We decided to try searching for the DTC signature ourselves," says Barrett, who notes that his team used MAP crystals simply because they were already available in their lab, leftover from another project.
The defining particularity of time crystals is that they "tick" when they're exposed to electromagnetic waves. This means that "their atoms spin periodically, first in one direction and then in another, as a pulsating force is used to flip them," explains the Yale news release.
The team used nuclear magnetic resonance to search for the DTC signature in their lab-grown MAP crystals and got striking measurements "right off the bat," Barrett points out.
"Our work suggests that the signature of a DTC could be found, in principle, by looking in a children's crystal growing kit."Aside from this unexpected discovery, Barrett's team also uncovered that the presence of the DTC signature "didn't necessarily prove that the system had a quantum memory of how it came to be," said research co-author Robert Blum, a Yale graduate student.
"This spurred us to try a time crystal 'echo,' which revealed the hidden coherence, or quantum order, within the system," revealed research co-author Jared Rovny, also a Yale graduate student.
Interestingly enough, according to ScienceNews, a separate team of scientists, from the Indian Institute of Science Education and Research in Pune, India, has also reported the discovery of a time crystal signature, this time in a liquid. Their experiment is described in a study also published in the Physical Review Letters on the same day.So, why are time crystals so important? For one thing, they could be used as a form of keeping time, since their molecules switch direction at regular intervals every time they're hit by pulses of electromagnetic waves, even if these pulses are uneven.
In addition, a better understanding of time crystals could help scientists improve the designs of atomic clocks, gyroscopes, and magnetometers. These elusive crystals could also be used to develop potential quantum technologies, notes the news release.