A German-Polish research team has captured the first video of space-time crystals, repeating structures of matter measuring micrometres in size at room temperature, marking a major step forward in finding applications for these fascinating objects.
A crystal is, by definition, a material whose building blocks are arranged in a lattice – a highly ordered microstructure. Time crystals are similar, but the order is in time rather than space. The structure changes and oscillates, periodically returning to a specific configuration.
Combining these two creates a space-time crystal. The crystal used in this study is Permalloy (an iron-nickel alloy) was attached to a small antenna through which a radio frequency current was sent.
This process creates certain excited states in the electrons of this material, which are called quasiparticles because they behave like particles (even though they are not particles). MagnonThe magnons in this material are seen to move in and out of alignment periodically in both space and time — a classic space-time crystal.
“We are able to show that these space-time crystals are much stronger and more widespread than originally thought,” said co-lead author Pawel Grsiecki, a scientist at the Department of Physics at Adam Mickiewicz University in Poznan. statement“Our crystals condense at room temperature and, unlike in isolated systems, the particles can interact with each other. Moreover, we have reached a size where we can use them to do things with this magnonic space-time crystal, which could give rise to many potential applications.”
What’s really exciting is that their space-time crystals can interact with other magnons that the researchers throw into the system: while two time crystals have interacted recently, this is the first time that a quasiparticle has been observed interacting with a space-time crystal.
“We took a regularly repeating pattern of magnons in space and time and sent more magnons into it, and eventually they scattered. Thus, we were able to demonstrate that time crystals can interact with other quasiparticles. No one has yet been able to show this directly in an experiment, let alone on video,” explained Nick Troger, a doctoral student at the Max Planck Institute for Intelligent Systems and the other co-lead author.
Crystals are useful in a variety of technologies, so there is great interest in how time crystal structures can be used in communications and imaging technologies.
This study Physics Review Letter.
An earlier version of this article was published at February 2021.