Researchers have made a groundbreaking discovery, unveiling entanglement between quarks and gluons within protons, marking a significant advancement in quantum physics. This remarkable finding, published in the journal Reports on Progress in Physics on December 2, 2024, provides the first direct evidence of such entanglement at an astonishingly small scale of one quadrillionth of a meter. The study harnessed data from the Large Hadron Collider (LHC) and the Hadron-Electron Ring Accelerator (HERA), two of the most advanced particle collider experiments.
The phenomenon of entanglement, where particles share information across vast distances, was initially dismissed by Albert Einstein as "spooky action at a distance." However, subsequent experiments validated its reality. Entangled particles remain interconnected, causing an instantaneous change in one particle to affect its partner, regardless of the distance separating them. This discovery marks the first time evidence has been found indicating that quarks inside protons are quantumly connected, a major leap from previous observations of entanglement between quarks.
Quarks and gluons serve as the fundamental building blocks of protons and neutrons, which are collectively known as baryons. Baryons consist of three quarks bound together by gluons, carriers of the strong force. The study of entanglement within these fundamental components is still relatively new and largely unexplored. Researchers had previously observed entangled quarks but never within the confines of a proton itself.
Zhoudunming Tu, a physicist at Brookhaven National Laboratory and co-author of the study, remarked on this new perspective:
"For decades, we've had a traditional view of the proton as a collection of quarks and gluons, and we've been focused on understanding so-called single-particle properties, including how quarks and gluons are distributed inside the proton."
The complexity of this research cannot be understated. The task involved sifting through the decay products of trillions of particles to reconstruct their original state, a process likened to assembling a complex puzzle without knowing what the final picture should look like.
The researchers plan to further explore this quantum connection using the Electron-Ion Collider (EIC), expected to be operational in the next decade. This next-generation collider will provide an even more detailed look at particle interactions and entanglement within nuclear structures. Tu highlighted the potential implications for understanding nuclear structure:
"Because nuclei are made of protons and neutrons, it is natural to ask what would the entanglement do to nuclei structure."
The study's findings not only challenge existing conceptions of particle physics but also offer new insights into the nature of entropy in quantum mechanics. Tu elaborated on this relationship:
"Entropy is usually associated with uncertainty on some information, while entanglement leads to information 'sharing' between the two entangled parties. So these two can be related to each other in quantum mechanics."
This research represents a significant step forward in our understanding of quantum mechanics and the fundamental forces that govern our universe. It opens new avenues for exploring how entanglement influences not just individual particles but also complex systems like atomic nuclei.
Ben Turner, a U.K.-based staff writer at Live Science, reported on this pivotal study, bringing attention to its potential to reshape our comprehension of quantum physics.
