For the first time, physicists have captured an enigmatic video of the matter.
Using a scanning transmission X-ray microscope, the research team has recorded the oscillations of a temporary crystal formed by magnons at room temperature. According to them, this represents a significant advance in the study of time crystals.
“We were able to show that these space-time crystals are much more robust and widespread than previously thought,” said physicist Pawel Gruszecki of Adam Mickiewicz University in Poland.
“Our crystal condenses at room temperature and particles can interact with it, unlike an isolated system. In addition, it has reached a size that could be used to do something with this space-time magnetic crystal. This can give rise to many potential applications. “
The crystals of time, sometimes also called space-time crystals, and which are only confirmed to exist a few years ago, are as fascinating as their name suggests. They look a lot like normal crystals, but for an additional property.
In regular crystals, the constituent atoms are arranged in a fixed, three-dimensional grid structure: think of the atomic lattice of a diamond or quartz crystal. These repeating latticework may differ in configuration, but within a given formation they do not move much: they are only spatially repeated.
In time crystals, atoms behave differently. They oscillate, turning first in one direction and then in the other. These oscillations, known as “tic”, are blocked at a regular and particular frequency. Therefore, where the structure of regular crystals is repeated in space, in time crystals it is repeated in space i time.
To study time crystals, scientists often use ultra-cold Bose-Einstein condensates of magnum quasiparticles. Magnons are not true particles, but consist of a collective excitation of the rotation of electrons, like a wave propagating through a network of spines.
The research team led by Gruszecki and his partner, PhD student in physics Nick Träger of the Max Planck Institute for Intelligent Systems in Germany, did something different. They placed a strip of magnetic permalloy on an antenna through which they could send a radio frequency current.
This current produced a magnetic field oscillating in the band, with magnetic waves traveling from both ends; these waves stimulated the fringe magnons, and these moving magnons condensed into a repetitive pattern.
“We took the pattern of periodically recurring magnons in space and time, sent more magnons into them, and they eventually dispersed,” Träger said. “Thus, we have been able to show that the time crystal can interact with other quasiparticles. No one has yet been able to show it directly in an experiment, let alone in a video.”
The video above shows the magnetic wavefront propagating through the strip, filmed up to 40 billion frames per second using the MAXYMUS X-ray microscope at Helmholtz’s BESSY II synchrotron radiation facility Zentrum from Berlin to Germany.
Time crystals need to be stable and consistent over long periods of time, because they theoretically oscillate in their lowest possible energy state. The team’s research shows that driven magnonic time crystals can be easily manipulated, opening up a new way to reconfigure time crystals. This could open up the state of matter for various practical applications.
“Classical crystals have a very wide field of application,” said physicist Joachim Gräfe of the Max Planck Institute for Intelligent Systems.
“Now, if crystals can interact not only in space but also in time, we add another dimension to possible applications. The potential of communication, radar or image technology is enormous.”
The research has been published in Physical review letters.