In an experiment that seemingly defies the laws of physics, scientists have created the first two-body crystal system in time, and it may have some incredible implications for the future of quantum computing.
In an article published today in the journal nature communicationsResearchers from the UK, Russia, and Finland described how they created two time crystals inside a superfluid — in this case, a rare isotope of helium, cooled to about one ten-thousandth of a degree from absolute zero — and brought them together to touch each other. , creating a coupled system that is not based on classical physics, but on quantum rules.
“Turns out putting two of them together works wonderfully,” explained Dr. Samuli Autti, member of the EPSRC, lead author of the study. “Even if time crystals shouldn’t exist in the first place.”
“Time Crystals” may sound like something out of a Indiana Jones movie, but in reality they are much more incredible than that. They are one of those strange quantum phenomena that baffles scientists a bit: their existence was only proposed in 2012and for a long time it was assumed that they were purely theoretical.
Imagine the collective surprise of the scientific community, then, when two separate research teams announced the discovery of some real-life time crystals. in 2017. Since then, the mysterious little objects have appeared everywhere, from state-of-the-art quantum computers a a toy for children every day.
but what exactly are time crystals? Depending on how you think about it, they are either exactly what they sound like or nothing like that at all. See, a normal, timeless crystal, something like an emerald or a snowflake, is defined by its regular, repeating atomic structure. A diamond, for example, looks like this under the microscope:
It is extremely symmetric: no matter where you are in the structure space, the pattern will be identical. And the time crystals are the same, except that the structure is not repeated in space, but in time.
This is the way to understand time crystals where their name makes a lot of sense: they are the time analog of a normal crystal. The slightly more confusing aspect comes when you try to imagine what that actually looks like.
“Let’s say you took pictures of a planet and its orbiting moon every time it ends its orbit over a period of time with the Hubble Telescope,” explained Google Quantum AI research scientists Pedram Roushan and Kostyantyn Kechedzhi, who were not involved in the research. “All of these images would look the same with the moon repeating its orbit over and over again.”
But “what if there were a system of one planet and many moons where the moons could periodically repeat their orbits, never increasing entropy?” they continued. “This configuration, obviously difficult to achieve, would be considered a time crystal.”
In other words, a time crystal isn’t really a crystal at all, at least not the way we’re used to thinking of them. It is a new phase of matter, simultaneously stable and constantly evolving at the same time, and always periodically returning to the same pattern.
And that… shouldn’t make sense. “Everyone knows that perpetual motion machines are impossibleAutti said. “However, in quantum physics perpetual motion is fine as long as we keep our eyes closed.”
“By sneaking through this crack, we can make time crystals,” he explained.
But creating a two-body time crystal system is more than just a way to circumvent the laws of physics. The Basic Building Block of a Quantum Computer: Widely Considered the next big jump in computing, it’s something called a “two-level system”: a quantum system that exists in a superposition of two independent quantum states. And that is exactly what the researchers have constructed: “In our experiments, two coupled time crystals consisting of spin-wave quasiparticles… form a two-level macroscopic system,” the article explains.
“The two levels evolve over time intrinsically determined by nonlinear feedback, which allows us to build spontaneous two-level dynamics,” the authors continue. “[The] Magnon time crystals allow access to all aspects and details of coherent quantum interactions in a single run of the experiment.”
And that opens up some exciting possibilities for the future. Generally speaking, quantum computers rely on extremely cold temperatures; Google’s, for example, is kept below 50 millikelvinwhich is literally colder than the coldest place in the universe.
But “we already know [time crystals] they also exist at room temperature,” Autti said, so the discovery of this two-body system may provide a way to make quantum computers that can work without supercooling.
And that… would be extremely exciting.