Time crystals made of light may soon be part of our everyday lives, thanks to a team of scientists who created these scientific wonders recently. Converting light into a way to quantify time is an endeavor that many have tried over the years, with some success.
But a new way to create these structures shows that they may be so easily made that they could even find their way into the electronics that we use every single day.
All crystals — whether they are made of rock salt, like the one above, or the most expensive diamond in the world — are on one level just atoms that are arranged in a repeating pattern.
Time crystals use patterns created with light beams from lasers
But imagine if that pattern had to do with time.
The resulting creation is the basis for “time crystals,” which are quantum systems that have the predictably repetitive behavior of crystal patterns.
Massachusetts Institute of Technology physicist and Nobel laureate Frank Wilczek first came up with the concept for time crystals in 2012.
“It’s a way of kind of having your cake and eating it too,” explains Professor Wilscek. “I was teaching a course about symmetry in physics” involving crystals. “But I wanted to do something fresh, so I thought about well, why not think about higher-dimensional crystals, crystals in more dimensions than three. And to make it more physical, the extra dimension should be time.”
Now a team of physicists headed up by engineer Hossein Taheri from the University of California, Riverside, have actually constructed a time crystal made out of light, as reported in Scientific American this week. The paper on their work, published in Nature Communications, could help time crystals make the critical transition from theoretical physics into mass-produced practical devices.
Although a time crystal’s pattern repeats over time, it is much more than a conventional clock, in part because a clock requires some other form of energy to function; however, time crystals “tick” as a normal stable state, not because they are made to do so by any external force.
A new, unique state of matter
In a way, these crystals are like a pot of water that boils continually, never cooling down. Some scientists consider them actually as a new, unique state of matter that is marked by a persistently staying out of equilibrium. It is this feature that may make time crystals into pieces of precision timekeeping or even quantum information processing, according to Scientific American.
“Time crystals have gone from being a conceptual idea motivated by highly theoretical considerations to something that people are trying to use for technology,” says Wilczek, who was not involved in the new effort to create the crystals.
The team used a comparatively simple method involving piping twin beams of laser light into a millimeter-wide, disk-shaped crystal cavity — inside which the two beams constantly ricocheted off the sides, colliding against each other.
It is of the utmost importance to have just the right design for the cavity; in addition, the researchers precisely controlled the laser beams so that the reflected light produced odd patterns that could never accidentally emerge from light emitted by other sources, including ordinary light bulbs.
The laser light became truly diamond-like, with solitary waves, what the scientists call “solitons,” emerging and forming patterns with a predictable periodicity, marching perfectly like a musical beat, in essence creating the world’s first time crystal.
As Taheri explains, when you observe the light bouncing out of the concave disc, you would see a light intensity pattern with a unique periodicity that is created by the solitons making their way through the cavity.
Light-based time crystals may be used in precision timekeeping
This periodicity revealed a quantum system that naturally kept its own time, in essence making a light-based time crystal.
Making for an ability to be converted into everyday use, the team’s time crystal operates under relatively normal circumstances, not extreme conditions, such as in cryogenic temperatures, which is the case with many crystals.
Berislav Buca, a physicist at the University of Oxford, who did not participate in the study, says “From my perspective, this experiment is important because it works at (relatively) high temperatures. This makes it closer to complex processes we see in the real world around us.”
Another ground-breaking feature of the time crystal is that constructing it requires relatively few components, says Lute Maleki, the CEO of the photonic technology company OEwaves, who also is a co-author of the study.
“We are discovering a new world here”
“This is really a simple (device) architecture,” he emphasizes, adding “It should be accessible to a lot of (research) groups.” Maleki says that he hopes research in the future will use the crystal in both investigations of fundamental physics and real-life applications such as in precision timekeeping.
Although light-based time crystals may be a bit less accurate than atomic clocks, which are the most accurate timepieces in the world, their stability and ease of construction could make them optimal for communication or computation devices that must have very accurate timekeeping while also being able to function outside a laboratory, in real-world conditions.
Additionally, some common electronics fabrication techniques could possibly enable the time crystal’s implementation on chips, making it easier to add the system to existing consumer gadgets.
Another advantage is that physicists could study huge time crystals in the same way that they examine the properties of spatial crystals, as they have for decades, according to study co-author Krzysztof Sacha, who is a physicist at Poland’s Jagiellonian University.
“I think that is really opening a new (physics research) horizon,” Sacha points out.
Wilczek couldn’t agree more, stating “This is a whole new class of states of matter. It is very conceivable to me that, when you examine them, useful devices and other surprises will emerge. It’s virgin territory; we are discovering a new world here.”