Surprise! Space-Time Crystals Are Real

Bringing space-time crystals from theory to physics

In 2017, a team of physicists from UC Berkeley created a blueprint for a novel phase of matter: the time crystal. Publishing their work in the journal Physical Review Letters, many were surprised to learn the empirical recipe for concocting a real-world time crystal.

Enthusiastic about the development, researchers from Harvard University and the University of Maryland kept tabs on the recipe from its initial publication in a preprint server — and cooked up their own time crystals via two disparate methods: trapped ions, and lasers.

You can’t hold a time crystal in your hands and make a wish, and it doesn’t grow at home on some esoteric rococo table if you add tap water and salt and say a few trippy-sounding words. But for years, the time crystal concept was stuck on paper as a mathematical prediction. But then, at last, it existed in a lab at the quantum level.

Time crystals are very complicated things, but to simplify: consider a typical crystal.

Time crystals exhibit ‘temporal periodicity’

Crystals are a collection of atoms arranged in a repeating (periodic) pattern in 3D space. Before liquids become crystals, they have to occupy a volume of space homogenously — kind of like how water in a full cup will be basically the same anywhere within the cup.

However, when this symmetrical distribution of water crystallizes, its atoms form rigid structures that repeat — like a pattern. But this symmetry is not omnidirectional — the patterns only repeat in some directions, not all.

Back in 2012, Frank Wilczek — who’s a Nobel Laureate — predicted this periodicity (or selective repeating pattern) might extend into the fourth dimension. Yes, we’re talking about time. Wilczek thought a system in its lowest possible energy state would effectively “freeze” the crystal in space like any other crystal — and thus be observable.

Wilczek further argued that if these low-energy system atoms strayed from their initial position, time-translation symmetry — which is the notion that a single instant of time is the same as any other — would be broken.

Time-translation symmetry is kind of like flipping a coin, which gives us a 50/50 chance of getting heads or tails — and this probability holds no matter how long or short a time we take to do it. Just like the water example for spatial symmetry, other objects exist through time in much the same way — in a state we can call temporal periodicity.

Microsoft’s Station Q showed time crystals could work

Wilzcek’s four-dimensional crystal has temporal symmetry, which is to say it exists (or happens) at normal intervals through time. But he hypothesized that bringing time crystals to the lowest possible energy level might break this symmetry, which would be like flipping a coin in ten seconds with a 50/50 chance, but then doing it again in 20 seconds, and discovering the probability has somehow shifted to a 20/80 split.

Physics allows matter to spontaneously form crystals — or solid objects whose structure breaks repeating spatial patterns (or periodicity) — the laws of the physical universe should also let time crystals form spontaneously, breaking the symmetry of time. Wilczek’s hypothesis suspected this would be observable in the periodic behavior of several thermodynamic processes — like in a ring of ions rotating at their lowest energy state.

If it happened it might behave like a pendulum, capable of measuring time. “[T]he spontaneous formation of a time crystal represents the spontaneous emergence of a clock,” said Wilczek in an MIT Technology Review report.

Wilczek encountered difficulty in the theories for time crystals, but in 2016, a group of physicists working at Microsoft’s UC Santa Barbara research facility Station Q discovered how to correct for Wilczek’s difficulties. Under the leadership of the physicist Chetan Nayak who leveraged earlier research from Princeton University, Station Q proved that time crystals can spontaneously break with time-translation symmetry, and show periodicity through time.

Time crystals could enable cars to communicate via radar, enhance quantum computers, and more

There is much more to the story of time crystals, but the recent footage from 2021 was captured by a scanning transmission X-ray microscope called Maxymus at Helmholtz-Zentrum Berlin — and it gives us the first peek into the behavior of time crystals, which were initially created within a laboratory in 2016. This development anticipates “outstanding new opportunities in fundamental research,” read the recent study from Maxymus.

The new video serves as visual proof of time crystals temporal periodicity — which is a vacillating, pendulum-like “motion” from one configuration to another. The clock analogy is apt, since scientists suspect this discovery might someday be used to keep time, or even store memory in quantum computers of the future.

A doctoral student named Nick Träger — of the Max Planck Institute for Intelligent Systems in Germany — led the recent study in tandem with Physicist Pawel Gruszecki — of the Adam Mickiewicz University (Poland). Together, they forged a relatively massive time crystal at room temperature — at scales of several micrometers. This relatively “macro” scale distinguished Träger’s team from earlier efforts alone — to say nothing of actually capturing a time crystal on film.

Träger and his colleagues created a time crystal using magnons in a magnetic strip equipped with a microscopic antenna. This antenna caused an oscillating magnetic field via radio-frequency current.

In the video, you can see the magnetic waveguide structure absorb X-ray beams in the fading and reappearing lines — where darker regions signify X-ray absorption, in contrast to the lighter regions. In sum, this video depicts the periodic oscillation of matter in both time and space.

“It is a little bit confusing, but we induce the magnons in the strip electrically with an antenna on top of the structure,” said Träger in a report from VICE.

“One could imagine a scenario, where, for example, cars only communicate with each other by radar signals and ‘magnonic space-time-crystals’ could act as an efficient component in such systems,” explained Träger in the VICE report. And the applications go on: these time crystals could enhance imaging and communications technologies, radar, and advance research into nonlinear wave physics.