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Researchers lead by Gwendel Fève, a physicist at Sorbonne University in Paris, have discovered the first experimental evidence that certain quasi-particles are 'anyons', members of a third kingdom of particles that are not fermions or bosons.

Every last particle in the universe — from a cosmic ray to a quark — is either a fermion or a boson. These categories divide the building blocks of nature into two distinct kingdoms.

While Quasi-particles demonstrating fractional quantum hall effect and displaying a fraction of the charge of a single electron had been observed before, this research is the first that demonstrates that they match predicted anyon behavior.

In 1984, a seminal two-page paper by [Frank A Wilzczek], Daniel Arovas and John Robert Schrieffer showed that these quasiparticles had to be anyons. But scientists had never observed anyon-like behavior in these quasiparticles. That is, they had been unable to prove that anyons are unlike either fermions or bosons, neither bunching together nor totally repelling one another.

That's what the new study does. In 2016, three physicists described an experimental setup that resembles a tiny particle collider in two dimensions. Fève and his colleagues built something similar and used it to smash anyons together. By measuring the fluctuations of the currents in the collider, they were able to show that the behavior of the anyons corresponds exactly with theoretical predictions.

"Everything fits with the theory so uniquely, there are no questions," said Dmitri Feldman, a physicist at Brown University who was not involved in the recent work. "That's very unusual for this field, in my experience."

Journal Reference:
H. Bartolomei, M. Kumar, R. Bisognin, et al. Fractional statistics in anyon collisions [$], Science (DOI: 10.1126/science.aaz5601)

Original Submission