New class of particles capable of boosting quantum mechanics

Jan. 8 () –

Researchers at Brown University have observed a new class of particles that may lead to new ways of exploring quantum phenomena, with implications in technology and computing.

Specifically, as published in ‘Nature’these are so-called fractional excitons, which behave in unexpected ways and could significantly expand scientists’ understanding of the quantum realm. “Our findings point to a completely new class of quantum particles that have no total charge, but they follow unique quantum statistics“Comet Jia Li, associate professor of physics at Brown.

“The most exciting thing is that this discovery opens up a range of new quantum phases of matter, presenting a new frontier for future research, deepening our understanding of fundamental physics and even opening up new possibilities in quantum computing,” he adds. in a statement.

The team’s discovery focuses on a phenomenon known as the fractional quantum Hall effect, which is based on the classical Hall effect, in which a magnetic field is applied to a material with an electric current to create a lateral voltage. The quantum Hall effect, which occurs at extremely low temperatures and high magnetic fields, shows that this lateral voltage increases in clear, separate steps. In the fractional quantum Hall effect, these steps become even more peculiar, as they increase by only fractional amounts, carrying a fraction of the charge of an electron.

In their experiments, the researchers built a structure with two thin layers of graphene, a two-dimensional nanomaterial, separated by an insulating hexagonal boron nitride crystal. This configuration allowed them to carefully control the movement of electrical charges. It also allowed them to generate particles known as excitons, which are formed by combining an electron and the absence of an electron, known as a hole.

They then exposed the system to incredibly strong magnetic fields, millions of times stronger than Earth’s. This helped the team observe the new fractional excitons, who displayed an unusual set of behaviors.

Fundamental particles are usually classified into two categories. Bosons are particles that can share the same quantum state, meaning that many of them can coexist without restrictions. Fermions, on the other hand, follow what is known as the Pauli exclusion principle.which says that no two fermions can exist in the same quantum state.

However, the fractional excitons observed in the experiment did not fit neatly into either category. Although they had the fractional charges expected in the experiment, their behavior showed tendencies of both bosons and fermions, acting almost like a hybrid of the two. That made them more similar to anyones, a type of particle found between fermions and bosons; However, fractional excitons had unique properties that also differentiated them from anyones.

“This unexpected behavior suggests that fractional excitons could represent a completely new class of particles with unique quantum properties,” Zhang argues. “We show that excitons can exist in the fractional quantum Hall regime and that some of these excitons arise from the pairing of fractionally charged particles, creating fractional excitons that do not behave like bosons.”

The existence of a new class of particles could one day help improve the way information is stored and manipulated at the quantum level, leading to faster and more reliable quantum computers, the team of researchers notes. “We have basically opened up a new dimension to explore and manipulate this phenomenon, and we are just beginning to scratch the surface,” Li points out. “This is the first time we have experimentally demonstrated that these types of particles exist, and now we’re delving deeper into what might come from them.”

The team’s next steps will involve studying how these fractional excitons interact and whether their behavior can be controlled. “It seems that we are hitting the button on quantum mechanics. “It is an aspect of quantum mechanics that we did not know or, at least, did not appreciate until now.”the researchers conclude.