On a quiet pandemic afternoon in 2021, Zhiyuan Wang, a graduate student at Rice University, was tackling strange mathematical problems to alleviate boredom. After he found an exotic solution, he began to wonder if he could physically interpret mathematics. Eventually, he realized that it appears to describe a new type of particle. It is not the particle in question or the particle carrying force. It seemed to be something completely different.
The King wanted to develop an accidental discovery into this complete theory of the third particle. He brought the idea to his academic advisor, Kaden Hazzard.
“I said, I don’t know if I believe this is true or not,” recalls Hazzard.
You might like it
In January this year, Wang and Hazzard, postdoctoral researchers at the Max Planck Institute of Quantum Optics Institute in Germany, published sophisticated results in the journal Nature. They say that there may actually be a third class of particles called paraparticles, and these particles can produce strange new materials.
When the paper came into view, Markus Müller, a physicist at the Institute of Quantum Optics and Quantum Information in Vienna, was already fighting the concept of paralysis for a different reason. According to quantum mechanics, an object or observer can be in multiple locations at once. On paper, Muller was thinking about how observer perspectives could be switched in these coexistent reality “branches.” He realized that this had new limitations regarding the possibility of paralysis, and his team explained the results in a February preprint, which is currently being reviewed for publication in the journal.
The close timing of the two papers was by chance. Together, however, the work resumes a mysterious case of physics that was believed to have been resolved decades ago. The basic question is being reassessed: What particles does our world allow?
Related: First, physicists find elusive “free range” atoms – confirm a century ago theory of quantum mechanics
The hidden world
All known basic particles fall into one of two categories, with the two acting as roughly opposite. There are particles that make up a material called fermions and particles that impart basic forces called bosons.
A characteristic of fermions is that when you switch positions of two fermions, their quantum states acquire negative signs. The presence of that slight negative sign has a major impact. This means that two fermions cannot be found in the same place at the same time. If you stuff them together, you won’t be able to compress the fermion past a certain point. This feature prevents material from collapse into itself. That’s why electrons in every atom exist in the “shell.” Without this negative sign we could not exist.
There are no such restrictions on bosons. The boson group is happy to do everything exactly the same. For example, any number of light particles can be in the same place. This allows for the construction of lasers that emit many identical light particles. This ability comes down to the fact that when two bosons exchange locations, their quantum states remain the same.
It’s not clear that Fermions and Bosons are the only two options.
This is partly due to the fundamental features of quantum theory. To calculate the probability of measuring a particle in a particular state, you need to take a mathematical description of that state and multiply it by itself. This step can erase the distinction. For example, the negative signs disappear. If you are given number 4, it’s dangerous! Contestants will have no way of knowing whether the question is “two squares.” Or “What is Negative 2 Square?” – both possibilities are mathematically valid.
Thanks to this feature, the fermion looks the same when measured, despite it gaining a negative sign when replaced. This indistinguishable is an important property of the basic particles. You cannot experiment with two types being apart.
However, it may not be just negative signs that disappear. In theory, quantum particles may have mathematical structures that are not seen in direct measurements, and hidden internal states that disappear even upon squared. The third, more common category of particle, known as particles, can arise from this internal state that changes in countless ways while the particles are exchanging.
Quantum theory appears to allow that, but physicists have had difficulty finding a mathematical description of functioning paralysis. In the 1950s, physicist Herbert Greene attempted several attempts, but further examination revealed that these paralysis models were truly typical mathematical combinations of bone and fermion.
In the 1970s, the mystery of why we were unable to find the right paralysis model seemed to be resolved. After mathematical physicists Sergio Dopricher, Rudolf Hague and John Roberts, a collection of theorems called the DHR theory proved that only bones and fermions are physically possible if certain assumptions are true. One assumption is “region”, the rule that objects can only be affected by things that are nearby. (As Hazzard said, “If I’m leaning at my table, I’d rather not have an instant effect on the moon,” DHR proof also assumed that the space was (at least) three-dimensional.
The results paralyzed new ventures for decades, with one exception. In the early 1980s, physicist Frank Willckek came up with a theory of particles called anyons, which could not be called either bosons or fermions. To avoid the DHR theorem, Anyons has a big catch. It can only exist in two dimensions.
Physicists are currently extensively studying Anyons on the possibilities of quantum computing. Although limited to two dimensions, it could appear on flat surfaces of material, or qubits in 2D arrays within quantum computers.
However, paralysis of three dimensions that could form solids still seemed impossible. That’s up to now.
The shift of the view
While developing the model, Wang and Hazzard realized that the assumptions behind DHR theory exceeded the typical concerns of the region. “I think people overinterpreted what restrictions and constraints were actually imposed by these theorems,” Hazzard said. They are paralysis that they realised that, after all, could be theoretically possible.
In their model, in addition to the usual properties of particles, such as charge and spin, the parapatil group shares extra hidden properties. Similar to the negative signs that are rectangular during measurement, these hidden properties cannot be measured directly, but they change the behavior of the particles.
When you exchange two paralysis, these hidden properties change in tandem. As an analogy, imagine these properties as colours. Start with two paralysis. One is red inside and the other is blue inside. Rather than retaining these colors, as defined by the mathematics of a particular model, they both change. Perhaps the swap leaves them green and yellow. This quickly turns into a complicated game, with paraparticles affecting each other in an invisible way as they move around.
Meanwhile, Mueller was busy rethinking the DHR theorem. “It’s in a very complicated mathematical framework, so it doesn’t always make what they mean very transparent,” he said.
His team took a new approach to the paralysis question. Researchers have come up with the fact that quantum systems can exist in multiple possible states at once, or what is called superposition. They imagined switching the viewpoints of observers present in these superposition states. If the two particles were really undistinguishable, they were thinking, but it doesn’t matter whether the particles were replaced with superimposed branches and not the other branch.
“Maybe if the particles are nearby, I’ll replace them, but if they’re far away, I’ll do nothing,” Muller said. “And if they’re in both superpositions, I’ll do swapping on one branch and nothing on the other.” Whether observers across the branch label two particles in the same way should not make a difference.
This more stringent definition of distinction in the context of superposition imposes new restrictions on the types of particles that may exist. If these assumptions apply, the researchers found that paralysis was impossible. Just as physicists expect basic particles, for a particle to be indeed indistinguishable by measurement, it must be a boson or a fermion.
Wang and Hazzard first published their paper, as if they had seen Müller’s constraints coming. Those paralysis is possible because the model rejects Mueller’s initiation assumption. Particles are not indistinguishable in the perfect sense necessary in the context of quantum superposition. This comes with consequences. Swap two paralysis, but one person’s measurements will not affect, but two observers can share the data with each other to determine whether the paraples have been replaced. This is because replacing the paralysis can change how the two people’s measurements relate to each other. In this sense, they were able to separate the two paralysis.
This means there is a possibility of a new material state. If a boson can pack an infinite number of particles into the same state and the fermions cannot share the state at all, the paralysis will be somewhere in the middle. They can cram just a few grains into the same state before they get crowded and force others into a new state. The exact number of people can pack together depends on the paraparticle details. Theoretical framework allows for endless options.
“Their papers are really fascinating and don’t contradict what we do,” Muller said.
The road to reality
If parapal grains are present, they are likely to be urgent particles called quasiparticles, which are displayed as energy vibrations of a particular quantum material.
“We may get a new model of the exotic phase that is difficult to understand before, but this can now be easily solved using paraparticles,” said Meng Cheng, a Yale physicist who was not involved in the study.
Bryce Gadway, an experimental physicist at Penn State, sometimes works with Hazard, but is optimistic that paralysis will be achieved in the lab over the next few years. These experiments use the Rydberg atoms, an energetic atom with electrons that walk very far from the nucleus. This separation of positive and negative charges makes Rydberg atoms particularly sensitive to electric fields. You can build quantum computers from interacting Rydberg atoms. He is also the perfect candidate for creating paralysis.
“For some kind of Rydberg Quantum Simulator, this is something they do naturally,” Gadway said of creating paralysis. “You just prepare them and see them evolve.”
But for now, the third kingdom of particles remains completely theoretical.
“Paralysis may be important,” said Wiltzek, a Nobel Prize-winning physicist and inventor. “But now, they are essentially theoretical curiosity.”
The original story was reproduced with permission from Quanta Magazine, an editorially independent publication supported by the Simons Foundation.
Source link
