Magical particle states found at the world's largest accelerator
When the heaviest known elementary particles are created at the LHC, a quantum phenomenon called magic occurs. This effect could make fault-tolerant quantum computers possible.
Quantum effects are commonplace at particle accelerators, but magic has never been observed there - until now. Two researchers have found evidence of so-called magic states in the data from the most powerful accelerator, the LHC near Geneva. These are quantum phenomena that cannot be simulated with ordinary computers. This concept from quantum computing could play an important role on the path to fault-tolerant quantum computers.
As the two physicists Christopher and Martin White - twin brothers, the former of whom conducts research at the University of London in England and the latter at the University of Adelaide in Australia - write in the journal "Physical Review D", they wanted to find out whether such magical quantum states also occur in accelerator experiments. Specifically, they investigated the production of top quarks, the heaviest fundamental particles. "Does nature produce magic top quarks, and if not, why not?" they ask. The answer to this question could help to utilise magic in natural quantum systems. This may reveal new types of experiments that provide better insights into the complicated and comparatively little researched quantum information phenomenon.
Normally, quantum physics is primarily concerned with long-known effects such as entanglement or the superposition of quantum objects. Magic first attracted attention in connection with quantum computers, in particular because of a publication from September 2024, in which Christopher White was also involved. The idea behind it is as follows: for truly powerful quantum computers, it is not enough to simply bring the computing units into superimposed and entangled states. In order for the devices to be superior to conventional computers in their calculations, further quantum properties are required that ensure, for example, a lower susceptibility to errors. Such properties are called magical. Conversely, the more magical a physical system is, the more difficult it is to simulate with a conventional computer. The choice of words may seem somewhat unscientific, but from a mathematical point of view, magic can be summarised in concrete formulas.
This is what the White brothers have done, searching for particle collisions in which magical states can be detected in the LHC experiments in which top quarks were created. In fact, the magic disappeared precisely when the entanglement became maximally large or minimally small during the production and decay of the top quarks. The two researchers now hope that the phenomenon can be utilised in various ways in physics. For example, accelerator data could be used to search for effects beyond the standard model if different theories make different predictions about magic. If quantum computing and particle physics can each be investigated using methods from the other field, this could lead to completely new insights.
Spectrum of Science
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