Key Points
- Quantum entanglement was observed between quarks for the first time at CERN.
- Researchers analyzed top and anti-top quarks, which live very short lives, preserving quantum information.
- ATLAS and CMS detectors confirmed the entanglement, with D values well below the threshold for entanglement.
- The finding opens the door for further tests of quantum entanglement at high energies, including experiments involving the Higgs boson.
Scientists at CERN, Europe’s renowned particle physics laboratory, have made a groundbreaking discovery by observing quantum entanglement between quarks for the first time. This remarkable achievement, announced in September, could pave the way for further exploration of quantum phenomena in high-energy environments.
Quantum entanglement, where particles lose their individuality and become interconnected so that they can no longer be described separately, has been well-documented in particles like electrons and photons. However, measuring this delicate phenomenon in particle collisions’ chaotic, high-energy environment has proven challenging.
Entanglement is typically easier to observe in low-energy, controlled settings like quantum computers. However, the Large Hadron Collider (LHC) at CERN, known for smashing protons together at incredibly high speeds, is a far noisier environment, making this observation particularly significant.
Physicists working with the ATLAS detector at the LHC analyzed around one million pairs of top and anti-top quarks—fundamental particles and their antimatter counterparts. The analysis yielded compelling evidence for quantum entanglement, later confirmed by another team working with the CMS detector. Both groups published their findings in Nature and the preprint server arXiv.
Top quarks, the heaviest known fundamental particles, live extremely short lives, lasting 10−25 seconds before decaying into longer-lived particles. During their brief existence, their quantum property known as ‘spin’ remains preserved. Researchers used the properties of these decay products to infer the original spins of the parent top quarks, confirming that they were entangled.
The concept of measuring entanglement at such high energies originated from a casual conversation between physicists Yoav Afik and Juan Muñoz de Nova. Their initial idea was later formalized into a research proposal, defining a parameter, D, to quantify the correlation between top quarks. The teams discovered that when D is less than -⅓, the quarks are entangled, with the ATLAS team measuring D at -0.537 and CMS at -0.480, both well below the threshold.
The discovery could lead to a deeper understanding of top-quark physics and expand the study of quantum entanglement to other particles, such as the Higgs boson. This breakthrough may even enable more rigorous tests of entanglement using high-energy colliders.
