For the first time, physicists have managed to create a strange and fragile structure known as the Rydberg trilobite molecule in the laboratory. The creation and observation of these exotic atomic structures gave scientists new information about the quantum activities of electrons distributed near atoms. Because their chemical bonds are unlike any other (as far as we know), this discovery paves the way for developing better theoretical models of the molecules and understanding their dynamics.

Rydberg molecules consist of a type of atom known as a Rydberg atom. An ordinary atom has a nucleus surrounded by a swarm of tiny electrons. If you add very little energy to an atom, the electron swarm swells a bit, making the atom slightly larger and puffier.

A Rydberg atom is what you get when you add a lot of energy under conditions that still allow it to retain its electrons. It explodes, quite large for an atom, micron in diameter, and the electrons are bound as loosely as they can without flying away. Because Rydberg atoms are so free, they behave in an exaggerated manner, making them useful for experiments.

Molecules are groups of atoms that come together in some way by combining electrons or perhaps with opposite charges. If you use a Rydberg atom you get a Rydberg molecule, but the way the atoms bond together can be very different from the bonds that hold normal molecules together.

And they can look very different, with electron distribution patterns that might resemble a trilobite or a butterfly, for example. A team of scientists in Gerwig Ott’s laboratory, led by physicist Max Alton from the University of Kaiserslautern-Landau, has created pure trilobite Rydberg molecules for the first time. They started by supercooling rubidium atoms to just 0.0001 degrees above absolute zero. They then used a laser to excite some atoms into Rydberg states.

“In this process, the outermost electron in each case is driven into distant orbits around the atomic body,” says Ott. “The orbital radius of an electron can be more than a micrometer, making the electron cloud larger than a small bacterium.”

A Rydberg molecule can be formed by transferring a ground-state atom that is not excited to the Rydberg state into the loose electron swarm of a Rydberg atom, where the two atoms are held together not by standard chemical bonds but by a peculiar bond. quantum attraction. .

“What glues them together is the quantum mechanical scattering of the Rydberg electron from the ground state atom,” Alton explains.

“Imagine the electron spinning rapidly around the nucleus. On each round trip, it collides with the ground state atom. Counterintuitively, quantum mechanics teaches us that these collisions lead to an effective attraction between the electron and the ground state atom.”

Due to repeated collisions, electrons scatter in an interference pattern that resembles the segmented shell of a trilobite. It also has other fascinating and strange features. The length of the molecular bond is almost the same as the Rydberg orbit, meaning it is quite large for atomic scales. The attractive force between an electron and an atom in the ground state is also quite high.

This means that Rydberg molecules have a higher electric dipole moment than other molecules; i.e. the distinction between positive and negative electrical charges, also known as polarity. The electric dipole moment of trilobite Rydberg molecules observed by Alton and colleagues is greater than 1,700 Debbies; This is extremely high. For water molecules, this measure is less than 2 deba.

The ability to not only create but also study pure trilobite Rydberg molecules provides physicists with a new tool for testing and understanding the quantum field. It also has potential applications for quantum information processing. And the researchers say it could be applied more broadly to study these strange molecules in different species.