For the first time, physicists captured an enigmatic state of matter on video.
Using a scanning transmission X ray microscope, researchers recorded the oscillations of a time crystal made-out of magnons at room temperature. At this, they said, is a significant break-through in the study of time crystals.
“Our crystal condenses at room temperature & particles can interact with it, unlike in an isolated system. Moreover, it’s reached a size that would be used to do something with this magnonic space-time crystal. This might result in many potential applications.”
Time crystals, sometimes also known as space-time crystals and only-confirmed to truly exist a couple of years ago, are as fascinating as the name suggests. They’re tons like normal crystals, but for an additional property.
In regular crystals, constituent atoms are arranged in a fixed, 3D grid structure, consider the atomic lattice of a diamond or quartz crystal. These repeating lattices can differ in configuration, but within a given formation they do not move around very much: they only repeat spatially.
In time crystals, atoms behave a bit differently. They oscillate, spinning first in one direction, then the other. These oscillations known as ticking, are locked to a regular & particular frequency. So, where the structure of regular crystals repeats in space, in time crystals it repeats in space & time.
To study time crystals, the scientists often use ultra-cold Bose-Einstein condensates of magnon quasiparticles. Magnons aren’t true particles, but consist of a collective-excitation of the spin of electrons like a wave that propagates through a lattice of spins.
The research team led-by Gruszecki & his colleague, physics doctoral student Nick Träger of Max Planck Institute for Intelligent Systems in Germany, did something different. They placed a strip of magnetic perm alloy on an antenna through which they would send a radiofrequency current.
That current produced an oscillating magnetic field on the strip, with magnetic waves travelling onto it from both ends, these waves stimulated the magnons in the strip and these moving magnons, then condensed into a repeating pattern.
“We took the regularly recurring-pattern of magnons in space & time, sent more-magnons in and they eventually scattered,” Träger said. “Thus, we were able to–show that the time crystal can interact with other quasiparticles. No one has yet been able to–show this directly in an experiment, let alone in a video.”
The video above shows, the magnetic wave-front propagating through the strip, filmed at up-to 40 billion frames per second using the MAXYMUS X-ray microscope at the BESSY II synchrotron radiation facility at the Helmholtz Zentrum Berlin in Germany.
Time crystals should be stable & coherent over long-time periods because they theoretically oscillate at their lowest-possible energy state. The team’s research shows, driven magnonic time crystals can often be easily manipulated, opening a new way tore-configure time crystals. This could open-up the state of matter for a range of practical applications.
“Classical crystals have a really broad field of applications,” said physicist Joachim Gräfe of Max Planck Institute for Intelligent Systems.
The research was published in Physical Review Letters.