Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have made a groundbreaking discovery about the inner workings of protons—the tiny particles that form the building blocks of atoms.
Using quantum information science and data from high-energy particle collisions, they’ve found evidence of quantum entanglement happening inside protons.
Quantum entanglement is a strange phenomenon famously called “spooky action at a distance” by Albert Einstein.
It describes how particles, even when separated, can remain connected and share information.
In the case of protons, entanglement happens at incredibly small distances—less than one quadrillionth of a meter—inside the proton itself.
The quarks and gluons, which make up protons, share information as a group through this entanglement.
This six-year study, recently published in Reports on Progress in Physics, changes how we view protons.
Traditionally, scientists thought of protons as a collection of separate quarks and gluons. Now, with the evidence of entanglement, it’s clear that protons are much more complex and dynamic than previously thought.
To explore entanglement, the researchers analyzed data from electron-proton collisions. These collisions, which smash particles together at extremely high speeds, help scientists study the structure of protons.
One of the key findings came from comparing the disorder, or entropy, in the particles produced during these collisions.
According to quantum science, if the quarks and gluons inside a proton are highly entangled, the resulting collisions should produce particles in a more “messy” or disordered way.
By studying data from experiments at the Large Hadron Collider and an earlier collider in Germany, the team confirmed their predictions.
The particle distributions matched the calculations for maximum entanglement perfectly, providing strong evidence for this phenomenon inside protons.
This discovery isn’t just about protons—it’s about the nature of matter itself. Quantum entanglement helps explain how quarks and gluons interact through the strong force, which binds them together inside protons.
Understanding entanglement could also solve larger mysteries in nuclear physics. For example, how does being part of a larger atomic nucleus affect the behavior of protons? Do the many particles in a nucleus disrupt or enhance entanglement?
These questions will be explored further at the Electron-Ion Collider (EIC), a major research facility planned to open in the 2030s. This collider will study how protons behave when they are part of a nucleus, using the tools and insights developed in this study.
Quantum entanglement is a system-wide interaction—it doesn’t just occur between two particles but among all the particles in a proton.
This collective behavior mirrors other areas of science. For instance, when you think of boiling water, the heat isn’t due to one water molecule but the combined energy of all the molecules. Similarly, understanding a single quark doesn’t reveal how the whole proton behaves.
By studying entanglement, scientists can simplify the seemingly messy process of particle collisions. Even though these collisions involve countless complex steps, some outcomes—like the disorder in the particles produced—are determined by the entanglement already present inside the protons before the collision.
With their model confirmed, the researchers are now turning their attention to new questions. They want to understand how the nuclear environment affects entanglement. When a proton is surrounded by other protons and neutrons in a nucleus, does this disrupt the entanglement or add new layers of complexity?
These questions could provide insights into quantum decoherence, a process where quantum systems lose their entangled states. It could also deepen our understanding of the strong force that governs interactions inside protons and nuclei.
The research tools developed in this study could be applied to many other phenomena in nuclear physics. As scientists continue to push the boundaries of what we know about matter, these discoveries will help unlock new frontiers in science.
This work not only reshapes our understanding of the proton but also offers a new way of thinking about quantum behavior in complex systems. The findings highlight the power of combining quantum information science with particle physics to uncover the hidden complexities of the universe.
Source: Brookhaven National Laboratory.
