(ORDO NEWS) — At the heart of every atom in the universe, whirling silently is a whirlwind of particles that physics craves to understand.
No probe, microscope, or X-ray machine can hope to make sense of the chaotic blur of quantum gears whirring inside an atom, leaving physicists to theorize as best they can based on the debris from high-speed collisions inside particle colliders.
Researchers now have a new tool that is already giving them a glimpse of the protons and neutrons that form the nuclei of atoms, based on the entanglement of particles that occurs when gold atoms slide off each other at speed.
Using the powerful Relativistic Heavy Ion Collider (RHIC) at the US Department of Energy’s Brookhaven National Laboratory, scientists have shown how precise data can be obtained on the location of protons and neutrons in gold using a kind of quantum interference never seen before in an experiment.
“This technique is similar to w “All doctors use positron emission tomography (PET) scans to see what is happening inside the brain and other parts of the body,” says physicist James Daniel Brandenburg, a former Brookhaven researcher and now a member of the STAR collaboration. .
“But in this case, we’re talking about mapping features on the scale of femtometers – quadrillionths of a meter – the size of an individual proton.”
From a textbook perspective, the anatomy of a proton can be described as three fundamental building blocks called quarks, bound together by the exchange of an interaction-carrying particle called a gluon.
If we zoomed in and observed this interaction with our own eyes, we would not see anything so neat. . Particles and antiparticles appear and disappear in a seething froth of statistical madness, where the rules for distributing particles are anything but consistent.
Putting restrictions on the motions and momenta of quarks and gluons requires some clever thinking. but hard evidence is what physicists really want.
Unfortunately, simply illuminating a proton will not produce a picture of its moving parts. Photons and gluons operate on completely different rules, which means that they are virtually invisible to each other.
However, there is a loophole. With enough energy, light waves can occasionally stir up pairs of particles that are on the brink of existence before disappearing again, among which are quarks and antiquarks.
If this spontaneous appearance occurs within earshot of an atom’s nucleus, the twinkling poltergeist of opposite quarks can mix with the spinning blasts of gluons and temporarily form a conglomerate known as a rho particle, which in a fraction of a second decays into a pair of charged particles called pions.
These pairs consist of a positive pion, consisting of an up quark and a down antiquark, and a negative pion, consisting of a down quark and an up antiquark.
Tracing the path and properties of the peonies thus formed can tell us something about the hornet’s nest in which it was born.
A couple of years ago, researchers at RHIC discovered that it was possible to use the electromagnetic fields surrounding gold atoms moving at high speed as a source of photons.
“In this earlier work, we demonstrated that these photons are polarized and their electric field radiates outward from the center of the ion,” says Brookhaven. physicist Zhangbu Xu.
“And now we’re using this tool, polarized light, to efficiently image nuclei at high energies.”
When two gold atoms narrowly avoid collision by spinning in opposite directions around the collider, photons of light passing through each nucleus can produce a rho particle and hence pairs of charged pions.
Physicists have measured the pions emitted by passing gold nuclei and have shown that they do indeed have opposite charges.
An analysis of the wavelike properties of the shower of particles showed signs of interference that can be traced back to the polarization of light, and hinted at something much less expected.
Under typical applied and experimental quantum conditions, entanglement is observed between the same kinds of particles: electrons with electrons, photons with photons, and atoms with atoms.
The interference patterns observed in the analysis of the particles obtained in this experiment could only be explained by the entanglement of non-identical particles – a negatively charged pion with a positively charged pion.
While far from being a theoretical anomaly, it is far from an everyday occurrence in the laboratory, constituting the first experimental observation of entanglement involving dissimilar particles.
By tracing the intricate interference patterns in gold’s nuclei, physicists have been able to reveal a two-dimensional portrait of its gluon distribution, allowing new insights into the structure of nuclear particles.
“Now we can take a picture where we can really discern the gluon density at a given angle and radius. ‘ says Brandenburg.
“The images are so accurate that we’re even starting to see the difference between the arrangement of protons and neutrons inside these large nuclei.”
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