CERN Physicists Confirm Quantum Entanglement in Extreme Higgs Boson Decays
Physicists working with CERN’s ATLAS collaboration at the Large Hadron Collider (LHC) have found strong evidence that quantum entanglement can persist under some of the most extreme conditions ever created in a laboratory.
Quantum entanglement at the Large Hadron Collider
Quantum entanglement— a phenomenon Albert Einstein famously called “spooky action at a distance”—is one of the fundamental features of quantum mechanics. It also plays a central role in quantum information science and quantum field theory.
“Today, it powers emerging technologies such as quantum computers, ultra-secure quantum communications networks, and next-generation sensors,” said Professor Alan Barr of the University of Oxford and his colleagues.
In quantum computing, entanglement allows multiple qubits to be manipulated in a single operation rather than individually. This makes it possible to perform multiple calculations simultaneously.
However, scientists had not known whether quantum entanglement would remain intact under extreme conditions involving short-lived particles produced in high-energy collisions.
Entangled Z bosons produced by Higgs boson decay
Using the LHC’s ATLAS detector, the researchers found strong evidence of entanglement between pairs of Z bosons. These heavy, short-lived particles were produced when a Higgs boson decayed.
The Higgs boson temporarily splits into two Z bosons. Each Z boson then rapidly decays into a pair of electrons or muons.
Although Z bosons disappear almost instantly, the ATLAS detector can track the electrons and muons produced by their decay. By studying these particles, the researchers inferred the Z bosons’ spins and reconstructed the angles at which the decay products traveled after the collision.
The collisions occurred at an energy of 13 trillion electron volts. The Higgs bosons were produced when protons traveling at 99.99% of the speed of light collided inside the LHC.
One of the highest-energy tests of entanglement
The result ranks among the highest-energy confirmations of quantum entanglement ever recorded. It extends a phenomenon often associated with delicate, small-scale laboratory experiments into the violent environment of high-energy particle collisions.
Professor Chris Timpson of the University of Oxford said: “Entanglement is both the most promising and the most puzzling aspect of quantum reality.”
“These collision-type experiments that detect entanglement present a new frontier in the study of the fundamentals of quantum mechanics,” he added.
Professor Daniela Bortleto of the University of Oxford said: “This measurement demonstrates the scientific power of the ATLAS collaboration and the unique capabilities of the LHC.”
Research paper
A paper describing the research was published in Physical Review Letters.
G. Ard et al. 2026. “Measurement of the entanglement of the Z boson pair in the decay of the Higgs boson in the ATLAS experiment.” Physical Review Letters 137, 111804. DOI: 10.1103/y1nh-1b82.
Source: www.sci.news