Scientists have achieved a major milestone in astrophysics by recreating a process theorized over 70 years ago: Fermi acceleration, the key mechanism behind cosmic ray generation. Using ultracold atoms and engineered optical barriers, researchers successfully built a controllable particle accelerator just 100 micrometres wide.
The experiment, conducted by scientists from the Universities o by Sophie Jenkins
London, UK (SPX) Jul 14, 2025
Scientists have achieved a major milestone in astrophysics by recreating a process theorized over 70 years ago: Fermi acceleration, the key mechanism behind cosmic ray generation. Using ultracold atoms and engineered optical barriers, researchers successfully built a controllable particle accelerator just 100 micrometres wide.
The experiment, conducted by scientists from the Universities of Birmingham and Chicago, involved colliding ultracold atoms with movable optical potential barriers. This allowed the team to simulate the energy-boosting dynamics originally theorized by Enrico Fermi in 1949. Though widely modeled in theory, this is the first experimental realization of the effect in a laboratory setting.
The compact accelerator propelled atoms at speeds exceeding half a meter per second and generated energy spectra similar to those seen in cosmic rays. This provided the first direct experimental validation of Bell's result, a foundational prediction in cosmic ray acceleration theory.
"Our Fermi accelerator surpasses the best-in-class acceleration methods used in quantum technology," said Dr Amita Deb of the University of Birmingham. "It features an exceptionally simple and miniaturised setup, and no theoretical upper limits."
This cold-atom-based system also demonstrated high-precision control, opening the door to detailed laboratory study of astrophysical events such as magnetic reconnection, shock wave acceleration, and turbulence. Researchers also see potential in developing new techniques for manipulating quantum wavepackets, with implications for quantum information science.
Co-lead author Dr Vera Guarrera added, "Our work represents the first step towards the study of more complex astrophysical mechanisms in the lab. The simplicity and effectiveness of our Fermi accelerator make it a powerful tool for both fundamental research and practical applications in quantum technology."
Future investigations will explore how various interactions influence the acceleration process, with goals ranging from advancements in atomtronics to deeper understanding of high-energy particle dynamics.
Research Report:Observation of Fermi acceleration with cold atoms
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