New type of entanglement allows us to see inside the atomic nucleus

Jan. 5 () –

Physicists of Brookhaven National Laboratory have found a new way to use a particle collider to see the shape and details inside atomic nuclei.

The method, applied in the RHIC (Relativistic Heavy Ion Collider) relies on particles of light surrounding gold ions as they move through the collider and a new type of quantum entanglement never seen so far.

Through a series of quantum fluctuations, particles of light (also known as photons) interact with gluons, glue-like particles that hold quarks together within the nuclei’s protons and neutrons. Those interactions produce an intermediate particle that rapidly decays into two “pions” of different charge. By measuring the speed and angles at which these positive and negative particles collide with RHIC’s STAR detector, scientists can go back to gain crucial information about the photon, and use it to map out the arrangement of gluons within the nucleus with greater precision than ever before.

SIMILAR TO CT SCANS TO SEE THE BRAIN

“This technique is similar to the way doctors use positron emission tomography (PET) to see what is happening inside the brain and other parts of the body”said former Brookhaven Laboratory physicist James Daniel Brandenburg, a member of the STAR collaboration who joined Ohio State University as an assistant professor in January 2023. “But in this case, we’re talking about mapping femtometer-scale features — quadrillionths of a meter-, the size of a single proton”.

Even more amazing, STAR physicists say, is the observation of an entirely new type of quantum interference that makes their measurements possible.

“We measure two outgoing particles and it’s clear that their charges are different – they are different particles – but we see interference patterns that indicate that these particles are entangled, or in sync with each other, even if they are distinguishable particles“, says Zhangbu Xu, a physicist at Brookhaven and a STAR collaborator, it’s a statement.

RHIC is a facility where physicists can study the basic building blocks of nuclear matter: quarks and gluons that make up protons and neutrons. They do this by colliding the nuclei of heavy atoms, such as gold, which are traveling in opposite directions around the collider at close to the speed of light. The intensity of these collisions between nuclei (also called ions) can “melt” the boundaries between individual protons and neutrons, so that scientists can study quarks and gluons as they existed in the early universe, before protons and neutrons were formed.