Swirling electrons could power future technology

Scientists have revealed a strange twister-like phenomenon in the quantum semimetal tantalum arsenide. The findings suggest that electrons move in swirling patterns that could reshape ideas in quantum electronics.

The research was led by Dr. Maximilian Ünzelmann, from the Universities of Würzburg and Dresden.

Multiple collaborators from different countries combined their efforts and used specialized approaches to pinpoint these curious swirls.

Understanding swirling electrons

Momentum space focuses on a particle’s energy and movement direction, not its physical location. Although vortices have appeared in other settings, watching electrons form a twister-like shape in this abstract space is a major step for modern physics.

Scientists previously verified similar behavior in position space, where tornado-like patterns appeared as visible rotations.

The earlier evidence hinted that these loops might also arise in momentum space, but they remained undetected until now.

Role of momentum space

Electrons in quantum materials can exhibit surprising behaviors when researchers track momentum, rather than standard coordinates.

This approach gives a snapshot of how electrons carry orbital angular momentum, a property that influences how they interact in electronic components.

Eight years ago, Roderich Moessner theorized that such structures might look like tiny smoke rings in momentum space. His idea suggested swirling motions could form whenever electrons cycle around certain atomic configurations.

Detecting quantum electron swirls

The team relied on angle-resolved photoemission spectroscopy, also known as ARPES, which is built on the photoelectric effect described by Albert Einstein.

“These experiments allow us to trace an important observable, the orbital angular momentum, of electrons in full 3D momentum space,” noted the researchers.

The technique involves shining light onto a sample and measuring energy details of the emitted electrons to piece together a material’s structure.

“When we first saw signs that the predicted quantum vortices actually existed and could be measured, we immediately reached out to our Dresden colleague and launched a joint project,” said Ünzelmann.

“By cleverly adapting this method, we were able to measure orbital angular momentum. I’ve been working with this approach since my dissertation.”

Producing the vortex signature

“The experimental detection of the quantum tornado is a testament to ct.qmat’s team spirit,” said Matthias Vojta, a professor of theoretical solid-state physics at TU Dresden.

In this environment, electrons circle in a manner that produces the vortex signature. That behavior signals fresh avenues for harnessing momentum-based features in electronic applications where electric charge may no longer be the only factor at play.

The sample of tantalum arsenide came from the US, while analytical work took place at a facility in Hamburg and included theoretical insights from a scientist in China and experimental support from a researcher in Norway.

Electron swirls and energy-efficient devices

This twister-like phenomenon might pave the way for orbitronics, a concept in which electrons’ orbital motion could move information through devices.

Researchers predict that tapping into orbital torque might lower energy losses compared to standard charge-based electronics.

Such technology could lead to faster components that generate less heat, a critical concern as devices pack in more processing power.

While it remains early in the discovery process, the swirling motion in tantalum arsenide shows promise for these future designs.

Quantum swirls reveal new possibilities

These results deepen our view of quantum materials by displaying electron activity in three-dimensional momentum space. The swirl patterns highlight how fundamental physics can unveil novel approaches in information transfer.

The research continues as the team explores exotic materials with similar vortex-like phases. The work is part of a broader push to understand how electrons behave under different symmetry conditions, possibly revealing even more unusual quantum states.

Breakthroughs in quantum technology

Future research will test whether tantalum arsenide or comparable materials can fuel next-generation orbital circuits.

Investigators hope that observing additional swirling effects might inspire design breakthroughs in quantum technologies.

Experts are also applying quantum tomography to piece together more details about these swirling electron states. Each advance could spark new theories or practical components that rely on momentum, angular momentum, and energy in ways never seen before.

The study is published in the journal Physical Review X.

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