In a first, scientists have managed to capture video footage of a space-time crystal, also known as an STC or simply a “time crystal,” revealing the eerie pulsations of this very trippy phase of matter.
Captured by Maxymus, a scanning transmission X-ray microscope at Helmholtz-Zentrum Berlin, the footage provides an unprecedented glimpse of the behavior of these novel time crystals, which were experimentally created in laboratory conditions for the first time in 2016. The discovery promises “outstanding new opportunities in fundamental research,” according to a study published this month in Physical Review Letters.
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At this point you may be understandably wondering: WTF is a time crystal? Fortunately, Motherboard has an in-depth response to this question that you can read here. But the short version is that these objects exhibit the properties of crystals in time as well as space. In the same way that the atomic lattices of crystals repeat regular patterns in space, time crystals repeat regular patterns in time.
In practical terms, this means that time crystals show what’s called temporal periodicity in which they oscillate between one configuration and another, like clockwork. For this reason, scientists have speculated they could eventually be used as time-keeping devices or as a future means to store memory in quantum computers.
The hypothetical existence of time crystals was first envisioned by Frank Wilczek, a Nobel-Prize-winning physicist, in 2012. By 2017, scientists at both the University of Maryland and Harvard University announced that they had successfully concocted nanoscale time crystals at very cold temperatures in their labs.
In the new study, researchers co-led by Nick Träger, a doctoral student at Max Planck Institute for Intelligent Systems in Germany, and Pawel Gruszecki, a physicist at the Adam Mickiewicz University in Poland, created a much bigger time crystal, at room temperature, that measured several micrometers in scale. These factors distinguished the team’s experiment from past studies, even without the added innovation of capturing the time crystal on film.
The German-Polish team created their time crystal from magnons, which are quasiparticles associated with the spin wave of electrons within a magnetic material. In an email, Träger suggested that an easier way to think about this concept is to imagine magnons as analogous to photons. In the same way that photons are the quantization of light, a magnon is the quantization of the spin wave inside a magnetic material.
“Summarizing, magnons are the ideal candidate for the observation of such space-time-crystalline formations because they are comparatively large and thus, directly measurable with our microscope,” Träger explained. “Additionally, the generation of magnons can be easily done at room-temperature which is a major advantage.”
In their experiment, Träger and his colleagues built a time crystal from magnons in a magnetic strip with a microscopic antenna attached to it. The antenna was used to generate an oscillating magnetic field using a radio-frequency current. The lines that fade in and out of the video show the absorption of the X-ray beam by this magnetic waveguide structure; the darker regions show where more X-rays are absorbed, compared to the brighter regions. The end result is a visualization of a periodic oscillation 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,” Träger said. “Thus, everything you can see in this video is a periodic magnetization pattern (consisting of magnons), which follows a space-time periodic motion.”
In addition to opening up a mind-boggling visual window into time crystals, these microscale, room-temperature time crystals could have potential applications for communication, radar, and imagining technologies, and investigating nonlinear wave physics, among many other possible fields, according to the researchers.
“Our team, as experimental scientists, are mainly focused on the fundamental aspect of these results and indeed, there are countless possibilities,” Träger said. “For the beginning, we want to gain a more fundamental understanding of the time oscillation of a space-time-crystal,” including the interactions of this magnonic space-time-crystal with other magnons, which is described in the paper.
“The possibilities for applications in the future are difficult to foresee,” he concluded. “But maybe at some point, it will be interesting for radar communication or quantum computing, where you need very efficient devices for frequency shifting. 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.”
