Everything in our universe is made up of atoms, from the human body to the air we breathe. Based on existing theoretical models, a unit contains three smaller subatomic particles, namely protons, electrons, and neutrons.
Protons and neutrons, which are the heaviest among the three, are found within the center of the nucleus of an atom. It is surrounded by a cloud of lightweight electrons with a radius measuring around 10,000 times larger than the nucleus.
With all this space, electrons are able to move freely at a distance, leaving an empty void that scientists at the Vienna University of Technology and Harvard University attempted to fill with other smaller atoms.
According to a paper published Feb. 22 in the Physical Review Letters journal, the team reports creating a computer-generated model of a giant atom filled with more than a hundred other smaller atoms.
Notably, this modified unit is characterized by an "exotic" interaction that occurs only in extremely low temperatures, giving scientists a deeper understanding of the unexplored field of "ultracold atoms."
Creating Giants Out Of Rydberg Atoms
To create this entirely new form of giant atoms, scientists had to start out with Rydberg atoms, which are comprised of one or more electrons that are highly excited. As a result, they orbit the nucleus from a larger distance, producing more vacant space.
The intricate process began with the production of a Bose-Einstein condensate from strontium atoms by cooling a diluted gas of subatomic particles named "bosons" to a temperature closest to absolute zero.
Using laser technology. the energy was transferred into one of the atoms in the condensate, turning it into a Rydberg atom with a larger radius. Neutral atoms were then scattered inside the empty space.
A total of 170 strontium atoms can be placed inside a giant atom. This number depends on two factors, such as the Rydberg atom's radius and the Bose-Einstein condensate's density.
Surprisingly, these neutrally charged atoms hardly make an impact on the atom's existing electrons due to their lack of electrical charge. However, the electrons are still somehow affected because they are blocked from changing into a different state.
Computerized models reveal that overall, the interaction weakens the energy of the entire system while forming a bond between the Rydberg atoms and the smaller atoms scattered along with electrons.
"Normally, we are dealing with charged nuclei, binding electrons around them. Here, we have an electron, binding neutral atoms," claims coauthor and VU professor Shuhei Yoshida in a report, describing the interaction as "highly unusual."
Exploring The Nature Of Ultracold Atoms
Scientists call this irregular state of matter as "Rydberg polarons." It could only be detected in extremely cold temperatures, but if it gets warmer, subatomic particles would start moving faster, causing the bond to break.
"For us, this ... is an exciting new possibility of investigating the physics of ultracold atoms," shares coauthor and VU professor Joachim Burgdörfer, adding that through such field, scientists can finally investigate the smaller components of a Bose-Einstein condensate.