CERN Scientists Successfully Laser-Cool Antimatter for the First Time

Trapped anti-atoms being cooled.
Credit: Chukman So

The result opens the door to considerably more precise studies of the response of antimatter to light and of how it behaves under the influence of gravity.

Swansea University physicists, as leading members of the ALPHA collaboration at CERN, have demonstrated laser cooling of antihydrogen atoms for the first time. The groundbreaking achievement produces colder antimatter than ever before and enables an entirely new class of experiments, helping scientists learn more about antimatter in future.

In a paper published on March 31, 2021, in Nature, the collaboration reports that the temperature of antihydrogen atoms trapped inside a magnetic bottle is reduced when the atoms scatter light from an ultraviolet laser beam, slowing the atoms down and reducing the space they occupy in the bottle — both vital aspects of future more detailed studies of the properties of antimatter.

In addition to showing that the energy of the antihydrogen atoms was decreased, the physicists also found a reduction in the range of wavelengths that the cold atoms can absorb or emit light on, so the spectral line (or color band) is narrowed due to the reduced motion.

This latter effect is of particular interest, as it will allow a more precise determination of the spectrum which in turn reveals the internal structure of the antihydrogen atoms.

Antimatter is a necessity in the most successful quantum mechanical models of particle physics. It became available in the laboratory nearly a century ago with the discovery of the positively charged positron, the antimatter counterpart of the negatively charged electron.

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