A bizarre new state of matter, known as a time crystal, has been created in the lab for the first time. While some may associate the word ‘crystal’ with crystal balls and jewellery, in scientific terms a crystal is a material that has a repeating atomic structure. Read more: Quantum computing and quantum supremacy, explained
This means if you started at one atom, and looked along any direction you chose, you would see a repeating pattern of other atoms. This structure happens a lot in nature, for example in snowflakes, salt or diamonds.
Now, researchers have created a completely new type of crystal, a time crystal, which repeats its pattern in time rather than space. The atoms in a time crystal never settle down, and are dubbed a ‘non-equilibrium’ phase. In addition to being a breakthrough in the study of matter, the strange material could be the key to achieving quantum computing.
“We have found a new phase of matter," said Soonwon Choi, a theoretical physics graduate student at Harvard University, and co-author of a new paper in Nature. "It's something moving in time while still stable.”
****: Time crystals were first proposed by theoretical physicist Frank Wilczek in 2012. They're hypothetical structures that appear to have movement even at their lowest energy state.
****: This works because of quantum mechanical effects, which mean atoms or ions can be interacting with each other while far apart.
****: In his original theory, Wilczek proposed a perpetual motion system, where atoms move with no energy being input into the system. But the new results are a little more complex than that.
Time crystals were first proposed by theoretical physicist Frank Wilczek in 2012. They're hypothetical structures that appear to have movement even at their lowest energy state. In January this year, Norman Yao from the University of California, Berkeley released a paper describing how a system like this could be built, but with ‘weaker’ symmetry than Wilczek had imagined.
"It's like playing with a jump rope, and somehow our arm goes around twice, but the rope only goes around once," Yao told Nature earlier this year. In Wilczek's version, the rope would oscillate all by itself. "It's less weird than the first idea, but it's still fricking weird."
Two separate teams of researchers, one led by the University of Maryland, and the other by Harvard University, took this blueprint and ran with it, creating two different versions of a time crystal that appeared equally viable.
"This opens the door to a whole new world of nonequilibrium phases," said Andrew Potter, an assistant professor of physics at the University of Texas at Austin.
"We've taken these theoretical ideas that we've been poking around for the last couple of years and actually built it in the laboratory. Hopefully, this is just the first example of these, with many more to come."
A team led by Chris Monroe of the University of Maryland built a time crystal, and Potter and Yao helped confirm that it indeed had the properties they predicted.
The bizarre material is made from ions of the element ytterbium. By applying an electrical field, the researchers levitated 10 of these ions above a surface. Next, they hit the atoms with a laser pulse, which caused them to flip. They then hit them again and again in a regular rhythm, which created a pattern of flips repeating in time.
A team led by Mikhail Lukin at Harvard University created a second time crystal a month after the first team, in that case, from a diamond.
“It shows that the richness of the phases of matter is even broader [than we thought]," Yao told Gizmodo.
"One of the holy grails in physics is understanding what types of matter can exist in nature. [N]on-equilibrium phases represent a new avenue different from all the things we've studied in the past."
One of the most promising applications for time crystals is quantum computing. Time crystals could potentially mean we can make much more stable quantum systems, which is one of the barriers to cracking quantum computing researchers are currently facing.
This article was originally published by WIRED UK
