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Artist's
impressions of skyrmions, which form as "whirlpools" of electron
spins |
Random numbers are crucial for computing, but our current algorithms aren’t truly random. Researchers at Brown University have now found a way to tap into the fluctuations of quasiparticles to generate millions of truly random numbers per second.
Random
number generators are key parts of computer software, but technically they
don’t quite live up to their name. Algorithms that generate these numbers are
still deterministic, meaning that anyone with enough information about how it
works could potentially find patterns and predict the numbers produced. These
pseudo-random numbers suffice for low stakes uses like gaming, but for
scientific simulations or cybersecurity, truly random numbers are important.
In recent years scientists have turned to the strange world of quantum physics for true randomization, using photons to generate strings of random ones and zeroes or tapping into the quantum vibrations of diamond. And for the new study, the Brown scientists tried something similar.
Skyrmions aren’t exactly particles, but particle-like effects that arise out of the arrangement of electrons. It starts by making sure all the electrons in a material have spins pointing in the same direction. Then, when this material is excited by electricity or a magnetic field, some electrons will flip their spins in the opposite direction to their peers. In doing so, it also warps the spins of the electrons surrounding the flipped one, creating a kind of whirlpool effect known as a skyrmion.
In this study, the researchers created magnetic thin films with defects that pinned skyrmions in place. This causes them to fluctuate randomly in size, wrapping themselves around other neighboring "pinning centers", shrinking and growing. Different skyrmion sizes produce different voltages through the material, and this can be measured to produce strings of random digits.
The researchers estimate that by optimizing how far apart the defects in the material are, this technique could produce up to 10 million random digits per second. This could be a huge breakthrough for cybersecurity, among other things.
“This
gives us a new way of generating true random numbers, which could be useful for
many applications,” said Gang Xiao, senior author of the study. “This work also
gives us a new way of harnessing the power of skyrmions, by looking at their
local dynamics as well as their global movements.”
References:
Wang, K.,
Zhang, Y., Bheemarasetty, V. et al. Single skyrmion true random number
generator using local dynamics and interaction between skyrmions. Nat Commun
13, 722 (2022). https://doi.org/10.1038/s41467-022-28334-4
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