Butterfly ultracold molecule completes a quantum “zoo” hunt

butterfly ultracold – A team led by Prof. Herwig Ott has created, for the first time, a huge “butterfly” molecule whose shape is written by electrons spread out like wings. Built from cooled rubidium atoms just above absolute zero and then laser-driven into an oversized quantum sta

For weeks. the lab’s lasers seemed to search for something that refused to show itself—an exact quantum configuration so specific that. as Prof. Herwig Ott put it. the team felt like they were trying to find an object on a road by inspecting just 1 millimetre at a time while standing a kilometre away.

What they finally built was a large, cold molecule that looks, in quantum terms, like a butterfly. Its “wings” are made from electrons. And with its successful creation, a long-running attempt to complete a “zoo” of similar ultracold molecules reached its endpoint.

Ott. from RPTU University Kaiserslautern-Landau in Germany. and his colleagues began by cooling rubidium atoms to a temperature only a few millionths of a degree above absolute zero. using lasers and electromagnetic forces. Cooling was only the opening move. The team then used lasers again to push each atom’s outermost electron very far from its nucleus—making the atoms very large in a controlled. laser-driven way.

In this enlarged, ultracold state, the quantum properties of the atoms can be manipulated precisely. The researchers leveraged that control to move a giant atom’s electron towards a normal-sized rubidium atom. When the electron and atom lock together. the system forms a new type of molecule—one with extreme properties shaped by how its electrons are distributed in space.

Each molecule came out at about 25 nanometres in size—bigger than the diameter of a DNA strand that contains billions of atoms. The responsiveness was even more striking: the molecules were thousands of times more responsive to electric fields than most molecules. Their overall shape is determined by the electrons. with the outermost electron spread out in a pattern that resembles the wings of a butterfly.

Ott said tuning the lasers just right was tricky enough to take weeks of tweaking before the team could create molecules with that exact configuration.

Team member Matthew Eiles. at Purdue University in Indiana. described the result as a culmination of earlier mathematical and experimental studies that helped narrow down the search. Based on mathematical models, researchers have spent 20 years searching for a “zoo” of giant ultracold molecules that ought to exist. Eiles said the new butterfly is the last one to be discovered.

The achievement is not only about finishing a checklist. It also points to a path toward creating more exotic and elusive ultracold molecules, including systems that could be very heavy as well as very large and charged, according to Michał Tomza at the University of Warsaw in Poland.

Weibin Li. from the University of Nottingham in the UK. stressed that while the butterfly molecule was difficult to create. it could now serve as a stepping stone. The idea is to use it as a precursor for making something even harder: ultracold atoms with negative charge. or anions. If anions can be cooled to ultracold temperatures. they could be used in tests of fundamental laws of particle physics or in studies related to antimatter. The problem, Li noted, is that standard cooling methods have failed to chill them so far.

Eiles and Ott have already mathematically investigated how to use the butterfly molecule to create ultracold anions. They hope to see the first signs within just a few years. Eiles’ message was blunt in its confidence: “The theory is already written.”

quantum physics ultracold molecules rubidium atoms laser cooling Rydberg atoms butterfly molecule electric fields anions particle physics antimatter