Shape of electrons is revealed for the first time through big advance in quantum physics

For the first time, researchers have measured the shape of an electron as it moves through a solid. This achievement could open a new way of looking at how electrons behave inside different materials.

Their discovery highlights many effects that could be relevant to everything from quantum information science to electronics manufacturing.

Those findings come from a team led by physicist Riccardo Comin, MIT’s Class of 1947 Career Development Associate Professor of Physics and leader of the work, in collaboration with other institutions. 

“We’ve essentially developed a blueprint for obtaining some completely new information that couldn’t be obtained before,” says Comin. His colleague and co-author, Mingu Kang, performed much of this research at MIT before continuing at Cornell University.

New angles on electron shape

Physicists have examined electrons for decades, but the wave-like aspect of these particles brings extra complexity. Electrons can be described not just as small points, but also as “wave functions.” 

These wave functions look like shapes or surfaces in higher-dimensional spaces. Sometimes these shapes are relatively simple. Other times, they’re tangled and tricky to measure. 

By using angle-resolved photoemission spectroscopy, or ARPES, the team recorded details about how electrons behaved as light hit them.

ARPES helped them pin down a previously elusive property of electrons that holds the key to better understanding their geometry.

Why electron shape matters

In usual settings, we talk about an electron’s energy or velocity. Those are familiar concepts. Geometry, on the other hand, points to the patterns or forms that electron waves can take when arranged in a solid. 

Quantum geometry affects how these particles interact, pair up, and even give rise to unusual behaviors. One example is superconductivity, where electrons zip along a material without resistance.

Another is when electrons form orderly patterns, a bit like a collection of synchronized dancers. Observing geometry could help scientists design new materials with novel electronic traits.

The kagome connection

The team measured this geometric effect in a class of materials called kagome metals. Kagome metals are named for a repeating pattern of atoms that resembles a series of interlocking triangles. This lattice structure can influence how electrons navigate and share energy. 

Physicists have long found kagome metals interesting because they host special behaviors that aren’t common in many other materials.

Observing the geometry inside them could explain why electrons in these metals sometimes align in peculiar ways that set off advanced superconductivity or other strange effects.

ARPES and quantum shapes

During ARPES experiments, researchers shine a beam of photons on a crystal. The light pushes electrons out of the material, allowing scientists to measure those electrons’ angles and spins.

By gathering that data, they reconstruct how electrons inside the crystal are moving and what shapes they form. 

This method is demanding because it requires intricate equipment and specialized facilities. Yet it gives a unique window into what happens on distances smaller than a billionth of an inch.

Applications and potential benefits

A precise measurement of quantum geometry can lead to progress in areas that rely on electron control. Quantum computing, for instance, depends on maintaining stable electronic states while performing computations. 

Researchers want materials that can reliably keep these states without unwanted disruptions. If scientists understand and possibly design the geometry of electrons, they might improve superconductors or even develop electronic devices that lose very little energy through heat.

With energy efficiency becoming ever more critical, there’s real value in controlling electron flow on such tiny scales.

Insights from global teamwork

This study was a partnership among institutions spanning different parts of the world. Collaborators brought together theoretical and experimental backgrounds.

Their collective expertise made it possible to design, synthesize, and measure the electronic structure of a kagome metal. 

The pandemic forced some members to work remotely, but it also enabled other team members to take on new roles in labs that were partially shut down.

That unexpected shift helped push the work forward and demonstrated how closely linked theory and experiment must be when tackling high-precision measurements.

One electron shape, many possibilities

Quantum geometry is far richer than standard geometry we learn in everyday math. The shape of an electron’s wave function isn’t like a typical circle or a neat sphere. It can take on forms that twist and loop in higher dimensions. 

Observing that shape in a real material confirms predictions that theorists have pursued for a long time. It means those theoretical constructs describing wave functions have real, measurable consequences.

And now, there is a proven route to measure them, so future studies might target exotic materials that exhibit other patterns or new behaviors.

What happens next?

Scientists plan to refine techniques like ARPES and adapt them to explore a range of materials. They hope to see how quantum geometry influences conductivity, magnetism, and other conditions that matter for practical applications. 

Physicists also see promise in discovering how manipulating geometry might encourage electrons to swap their usual habits for more synchronized, cooperative behavior.

That synchronization is important for technologies that rely on controlling multiple electrons at once, such as quantum sensors or memory elements.

Experts say these findings will likely inspire more ambitious experiments to uncover aspects of quantum geometry we haven’t been able to measure before. 

With each new result, materials researchers step closer to engineering designs for the electronic components of tomorrow. The electron might be tiny, but it’s revealing secrets about shaping the future of technology.

The study is published in Nature Physics.

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