Imagine a cat that is both alive and dead at the same time—a strange idea that physicists call a superposition. Now, scientists at the University of Basel in Switzerland have discovered something almost as strange happening inside tiny clusters of molecules. Electrons inside these clusters can exist in more than one place simultaneously, and this discovery could someday lead to faster computers and better phone technology.
The research team, led by Professor Ernst Meyer from the Swiss Nanoscience Institute, was studying extremely small clusters made of a specially designed molecule called TBTAP. They arranged these molecules into groups of three and six using a powerful tool called a scanning tunneling microscope, which can see and move individual molecules.
After applying different voltages (essentially, electrical pressure) to the clusters, the scientists made a surprising finding. The unpaired electrons inside neighboring molecules were not acting independently—they were influencing each other. The microscope images revealed beautiful ring-shaped, flower-like patterns showing where the electrical charge was distributed across the molecules.
"We found that, rather than being independent, the unpaired electrons in neighboring molecules influenced one another," said Dr. Chao Li, the study's lead author.
According to quantum mechanics (the physics that governs tiny particles), nature tends to favor a mixed state where charge spreads evenly across all molecules. However, the repulsion (push) between charges was so strong that one or two electrons were actually pushed out into the material beneath the cluster. In the three-molecule cluster, several charge combinations existed at once—meaning different molecules held the charge at different moments, all happening simultaneously. In some cases, a single charge was distributed across multiple molecules at the same time.
With six molecules, the behavior was slightly different: the inner molecules stayed neutral while the outer three carried the charge.
"The charges are no longer localized on an individual molecule but are instead present at several locations at the same time—just as Schrödinger's cat is simultaneously dead and alive," said Dr. Rémy Pawlak, who supervised the research.
The scientists also discovered something unexpected called negative differential conductivity—where electrical current actually decreased when voltage increased, a behavior that seems impossible in our everyday world. This effect could one day be useful for voltage-controlled oscillators in mobile phones or quantum computers.
The team was able to create computer models that precisely matched their experiments, allowing them to predict how charges behave in similar molecular clusters. This level of control is a crucial step toward developing a new generation of electronic components built at the molecular level.
"We've shown here that we not only understand complex interactions in molecular clusters but could also use them in a targeted manner," Meyer said. "That's a key step toward developing a new generation of electronic components on the molecular level."
The research, published in the journal Nature Communications, was a collaboration between scientists from Basel, Bern, Nanjing, and Prague.