Quantum computers are set to revolutionize the way informatic works by being way faster than our current devices. We do not yet have a quantum computer but many prototypes are getting closer and can do pretty cool stuff. Including creating new phases of matter, such as a time crystal, as reported in new research published in Nature.
First of all, let’s discuss how a quantum computer works. Instead of your regular bits made of zeros or ones, you have quantum bits or qubits which harness the power of quantum mechanics. They can be in superposition, they are entangled, all quantum properties that allow for incredibly fast calculations. Linking more qubits means exponentially faster computations.
But the challenge is that quantum systems are often delicate. They need to be kept at extremely low temperatures, in a vacuum, etc. These conditions are not ideal if we envision a portable quantum computer but they are great to study curious phases of matter.
And this is where the time crystal comes into play. A regular crystal is a collection of particles (molecules, atoms, etc) with a precise space structure that repeats itself. A time crystal is just like that but the structure doesn’t repeat in space. It repeats in time.
They have been observed only recently, and there is still much we don’t about them. This latest approach uses Google’s Sycamore quantum computing hardware to actually create a time crystal.
“The big picture is that we are taking the devices that are meant to be the quantum computers of the future and thinking of them as complex quantum systems in their own right,” Matteo Ippoliti, a postdoctoral scholar at Stanford and co-lead author of the work, said in a statement. “Instead of computation, we’re putting the computer to work as a new experimental platform to realize and detect new phases of matter.”
A time crystal changes through time but it goes back to the specific structure over and over again. The entropy of the system does not change, no energy is getting in and no energy is lost, so a perfect time crystal is expected to exist indefinitely.
Quantum devices are imperfect, meaning that the time crystal could only be observed for a few hundred cycles. But the team was able to study its properties with new protocols and simulations, that not only informed them of time crystals but also provided novel insights into quantum computers.
“We managed to use the versatility of the quantum computer to help us analyze its own limitations,” said Roderich Moessner, co-author of the paper and director at the Max Planck Institute for Physics of Complex Systems. “It essentially told us how to correct for its own errors, so that the fingerprint of ideal time-crystalline behavior could be ascertained from finite time observations.”
This is an exciting development. Quantum computers might be key to solving some of the major questions of science thanks to their computational power but they might also solve some questions just by being quantum devices.