Scientific breakthrough uses cold atoms to unlock cosmic mysteries 

Scientists have used ultracold atoms to successfully demonstrate a groundbreaking method of particle acceleration that could unlock new understanding of how cosmic rays behave, a new study reveals. 

After more than 70 years from its formulation, researchers have observed the Fermi acceleration mechanism in a laboratory by colliding ultracold atoms against engineered movable potential barriers – delivering a significant milestone in high-energy astrophysics and beyond. 

Fermi acceleration is the mechanism responsible for the generation of cosmic rays, as postulated by physicist Enrico Fermi in 1949.   The process itself features also some universal properties, that have spawned a wide range of mathematical models, such as the Fermi-Ulam model. Until now, however, it has been difficult to create a reliable Fermi accelerator on Earth. 

Publishing their findings today in Physical Review Letters, the international research team from the Universities of Birmingham and Chicago reveal their success in building a fully controllable Fermi accelerator and using this to observe significant particle acceleration. 

The accelerator - just 100 micrometres in size - can quickly accelerate ultracold samples to velocities of more than half a meter per second. It does this making movable optical potential barriers collide with trapped ultracold atoms.  

By combining energy gain and particle losses, the scientists can also obtain energy spectra analogous to those observed in cosmic rays - providing the first direct verification of the so-called Bell’s result, which is at the core of every cosmic ray acceleration model. 

Co-author Dr Amita Deb, from the University of Birmingham, commented: “Results delivered by our Fermi accelerator surpass the best-in-class acceleration methods used in quantum technology. The technology has the additional advantages of featuring an exceptionally simple and miniaturised setup, and no theoretical upper limits.” 

The accelerator’s generation of ultracold atomic jets demonstrates the potential for high-precision control over particle acceleration. The ability to study Fermi acceleration with cold atoms opens new possibilities for investigating phenomena relevant to high-energy astrophysics.  

Future areas of research include the study of particle acceleration at shocks, magnetic reconnection, and turbulence which are critical processes in the universe. Studying quantum Fermi acceleration could lead to the development of new tools for manipulating quantum wavepackets, offering promising avenues for advancements in quantum information science. 

Dr Vera Guarrera, one of the leading authors from the University of Birmingham, commented: “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.” 

The research team plans to further explore the applications of their Fermi accelerator in various fields, including quantum chemistry and atomtronics. They aim to investigate how different kinds of interactions affect the acceleration rate and the maximum energy attainable, providing valuable insights for both theoretical and experimental physics. 

ENDS  

For more information, interviews or an embargoed copy of the research paper, please contact the Press Office at University of Birmingham on pressoffice@contacts.bham.ac.uk or +44 (0) 121 414 2772.  

Notes to editor:  

• The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 8,000 international students from over 150 countries.  

• ‘Observation of Fermi acceleration with cold atoms’ - G. Barontini, V. Naniyil, J. P. Stinton, D. G. Reid, J. M. F. Gunn, H. M. Price, A. B. Deb, D. Caprioli, and V. Guarrera is published in Physical Review Letters