Scientists at Brookhaven National Laboratory have looked inside protons using high-energy particle collisions. They have used quantum information theory to understand how quantum entanglement affects particles streaming from electron-proton collisions.
Quantum entanglement means that particles like quarks and gluons, the parts that make up protons, can share information even when far apart. This happens over very tiny distances inside protons, less than one quadrillionth of a meter.
The team's work, detailed in a recent paper in Reports on Progress in Physics, shows how entanglement influences the spread of particles coming out of these collisions. It suggests that quarks and gluons are entangled, complicating our view of protons' inner workings.
Physicists usually consider quarks and gluons as separate entities within protons. Now, evidence of entanglement shows protons are more dynamic and complex.
This research could help answer questions about how protons behave within larger atomic nuclei, which will be studied at the upcoming Electron-Ion Collider (EIC). The study used quantum information science to predict the effect of entanglement on collision outcomes, looking at entropy as a sign of entanglement.
A messy room illustrates high entropy, like the particle distribution from entangled protons. If quarks and gluons are highly entangled, collisions result in a high-entropy particle spread. The scientists confirmed this by checking data from past experiments at HERA in Germany against their calculations.
Global entanglement
The findings reveal that entanglement is not just between two particles but among all particles in a system, potentially simplifying complex nuclear physics problems. The study shows that the collective behavior of quarks and gluons in protons is more telling than individual behaviors, much like how water's temperature arises from the collective vibrations of its molecules.
Future experiments at the EIC will explore how entanglement behaves when protons are part of a nucleus, potentially revealing more about quantum coherence or decoherence in nuclear environments.
This research opens new ways to understand the structure of matter and could impact other fields where quantum entanglement is key.
