Fractons, the strangest matter, could give quantum clues


Your table is composed of individual, different atoms, but its surface looks smooth. This simple idea is at the core of all our models of the physical world. We can describe everything that happens without getting stuck in the complicated interaction between each atom and electron.

Thus, when a new theoretical state of matter was discovered whose microscopic characteristics stubbornly exist at all levels, many physicists refused to believe in its existence.

“When I first heard about the fractons, I said there was no way it was true because it completely defies my prejudices about the behavior of the system,” he said. Nathan Seiberg, a theoretical physicist at the Institute for Advanced Study in Princeton, New Jersey. “It simply came to our notice then. I realized I was living in denial. ”

Theoretical possibility of fracton surprised physicists 2011. Recently, these strange states of matter have led physicists toward new theoretical frameworks that could help them solve some of the most difficult problems in fundamental physics.

Fractons are particle-like particle-like entities that result from complicated interactions between many elementary particles within a material. But fractions are even bizarre compared to other exotic quasiparticles, because they are completely immobile or can only move in a limited way. There is nothing in their environment that prevents the movement of the fracton; rather it is their inherent property. This means that the microscopic structure of fractons affects their behavior over long distances.

“It’s completely shocking. For me, it is the strangest phase of matter, “he said Xie Chen, a condensed matter theorist at the California Institute of Technology.

Partial Particles

In 2011, Jeongwan Haah, then a graduate student at Caltech, was looking for unusual phases of matter that were so stable can be used to secure quantum memory, even at room temperature. Using a computer algorithm, he opened a new theoretical phase called the Haah code. This phase quickly attracted the attention of other physicists because of the strangely immobile quasiparticles that make it up.

They seemed, individually, only as particles of particles, only in combination. Soon, several theoretical phases with similar characteristics were found, so in 2015, together with Haah Sagar Vijay i Liang Fucoined the term “fractons” for strange partial quasiparticles. (Earlier, neglected paper Claudio Chamon it is now attributed to the original discovery of fractal behavior.)

To see what is so exceptional in the fracton phases, consider a more typical particle, like an electron, that moves freely through a material. A strange but common way certain physicists understand this motion is that the electron moves because space is filled with electron-positron pairs that pop up in and out of existence for a moment. One such pair appears so that the positron (oppositely charged electron particle) is at the top of the original electron and they are canceled. This leaves behind an electron from the pair, displaced from the original electron. Since there is no way to distinguish two electrons, all we observe is the motion of one electron.

Instead, imagine that pairs of particles and antiparticles cannot form from a vacuum, but only their squares. In this case, a square could be formed so that one antiparticle lies on top of the original particle, nullifying that angle. The second square then pops out of the vacuum so that one side of it is canceled with the side from the first square. This leaves the opposite side of the second square, which also consists of a particle and an antiparticle. The resulting motion is the movement of a particle-particle pair moving laterally in a straight line. In this world – an example of a fracton phase – the motion of a single particle is limited, but the pair can move easily.

The Haah code takes the phenomenon to extremes: particles can only move when new particles are called in infinite repetitive patterns called fractals. Let’s say you have four particles arranged in a square, but when you zoom in on each corner you find another square of four particles that are close to each other. Zoom in on one corner again and you’ll find another square, and so on. In order for such a structure to materialize in a vacuum, so much energy is needed that it is impossible to move this type of fracton. This allows very stable qubits – quantum computing bits – to be stored in the system, because the environment cannot disturb the sensitive state of the qubits.

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