In the 127 years since the electron was discovered, it has undergone more scrutiny than perhaps any other particle. As a result, its properties are not just well known, but rote, textbook material: Electrons have a smidgen of mass and negative electric charge. In a conductor, they swim relatively unimpeded as a current; in an insulator, they barely move.
Over time, caveats have cropped up. Under an intense magnetic field, for example, electrons can lose their individual identities and form “quasiparticles”: collective entities, like the shape formed by a school of fish. But even these collective states have been well cataloged.
So it came as a shock last year when a new effect was seen in electrons. Researchers at the University of Washington reported in August 2023 that in a stack of two atomically thin crystalline sheets offset from each other at a slight angle, electrons behaved like quasiparticles with fractional amounts of charge, such as −⅔ and −⅗. A few months later, a team at the Massachusetts Institute of Technology reported the same effect in another material. It was the first time that electrons had formed fractional quasiparticles without the enabling influence of a magnetic field.
While predictions about the possibility of this particular effect date back to 2011, theorists are still puzzling over the new discovery. It’s not clear how the underlying mechanism works in the MIT group’s material; calculations from several groups neither fully explain the fractional states nor agree. Other, even odder quantum phases of matter may also be present.
The new discovery isn’t incidental, or specific to a material. Rather, it’s universal and fundamental — the result of the quantum nature of the electron, albeit a behavior that has until now stayed hidden. While condensed matter physicists want to understand the breadth of electron behaviors for their own sake, there’s always the chance of uncovering the basis of a world-changing technology. In this case, the newfound effect may carry the seeds of long-sought quasiparticles with stable memories that could underpin a new and powerful approach to quantum computing.
To read more, click here.