These results open a new perspective on the complex world of quantum physics.
Quantum entanglement is a fascinating feature of quantum physics – the theory of very small things. If two particles are quantum entangled, the state of the first particle is bound to the state of the second, regardless of how far apart the particles are. This mind-boggling fact, which has no analogue in classical physics, has been observed in a wide variety of systems and has found several important applications, such as quantum cryptography and quantum computers. In 2022, Alain Aspect, John F. Clauser and Anton Zeilinger were awarded Nobel Prize in Physics for groundbreaking experiments with entangled photons. These experiments confirmed the manifestations of quantum entanglement, which predicted the late CERN theorist John Bell and contributed to the beginnings of quantum computing.
Quantum entanglement has remained more or less unexplored at the high energies available at particle accelerators such as Large Hadron Collider (LHC). V articlewhich was published today in Naturecollaboration ATLAS described how, for the first time and at the highest energies to date, she successfully observed quantum entanglement at the LHC between fundamental particles called top quarks. This result, first reported by ATLAS in September 2023 and subsequently confirmed two observations carried out by collaboration CMSopened a new perspective on the complex world of quantum physics.
“Even though particle physics has deep roots in quantum mechanics, the observation of quantum entanglement in a new particle system and at a much higher energy than previously possible is remarkable,” said ATLAS spokesman Andreas Hoecker. “The continued accretion of data paves the way for new investigations of this fascinating phenomenon and opens up a rich menu for further research.”
The ATLAS and CMS collectives observed the quantum entanglement between the top quark and its antiparticle. These observations are based on recently proposed methodwhich uses top quarks produced at the LHC as a new system for studying quantum entanglement.
The top quark is the heaviest known fundamental particle. Under normal circumstances, it decays into other particles before it has time to combine with other quarks. Therefore, its spin and other quantum attributes are transferred to its decay products. Physicists observe the properties of the decay products to infer the spin orientation of the original top quark.
In order to observe quantum entanglement between top quarks, ATLAS and CMS selected pairs of top quarks from data from proton-proton collisions at 13 teraelectron volts, which were obtained in the second run of the LHC between 2015 and 2018. They focused on pairs in which top quarks they have little mutual momentum. In such a case, a strong quantum binding of the spins of both quarks is expected.
The existence and degree of quantum entanglement of spins can be deduced from the angle between the directions in which the electrically charged decay products of both quarks fly out. By measuring this angle and after correcting for experimental effects that could change its value, the ATLAS and CMS teams managed to observe the quantum entanglement of the spin of top quarks with a statistical significance greater than five standard deviations.
In his the second study the CMS collaboration looked at pairs of top quarks in which the produced quarks had large mutual momentum. In this area, it is true for a large percentage of top quark pairs that predictions of the relative positions and half-lives of the top quarks of the given pair exclude the classical exchange of information by particles not exceeding the speed of light. The CMS experiment observed spin quantum entanglement between top quarks in this case as well.
“Measurements of quantum entanglement and other quantum concepts in a new particle system and at energies above previously available values provide new ways of testing Standardof the model of particle physics, as well as new ways of searching for manifestations of new physics behind the Standard Model.”
Source: www.nextech.sk
