Research collaboration achieves world’s first laser-cooling of antimatter

March 31, 2021
Artistic illustrations of the movement of an antihydrogen atom in the ALPHA magnetic trap, before and after laser cooling (in grey before, and blue after.) The images show various lengths of the antihydrogen’s tracks. Credit: Chukman So

Simon Fraser University distinguished professor of physics Mike Hayden is part of an international research collaboration that has achieved the world’s first chilling of antimatter by using a laser. 

An article on this development, considered a breakthrough in the field of antimatter research, was published today and featured on the cover of the journal Nature. Laser cooling of ordinary atoms is a technique that has been developed over the last 40 years but this is the first time it has been applied to antimatter. 

The research collaboration, known as ALPHA, used laser cooling to chill antihydrogen atoms to temperatures as low as 0.012 degrees above absolute zero. This cooling slows the motion of anti-atoms, allowing researchers to perform more precise measurements of their properties, such as differences between internal energy levels. 

The goal is to compare these properties with those of the ordinary hydrogen atom. Subtle differences, if they exist, may offer clues to solving mysteries such as the glaring imbalance between matter and antimatter in our universe.

“The Big Bang should have produced antimatter and matter in roughly equal quantities, but that is not what we see,” says Hayden. “There is almost no antimatter in the universe. This research will help find answers to very fundamental questions about the universe we live in. This is a tool that will help us in that search.”

Future applications of the laser cooling method could include experiments to test the way in which antimatter responds to gravity, or perhaps even the creation of anti-molecules.

ALPHA researchers conduct antimatter experiments at CERN, a research facility located in Geneva, Switzerland.

Antimatter is destroyed when it collides with matter, and so it has to be held in a sophisticated, magnetic bottle in order to be studied. 

Hayden and his team at SFU lend their expertise in microwave physics to the project. This includes manipulating the internal states of the atoms, to prepare them for for the laser cooling experiment, and performing very precise measurements of energy intervals. 

“We’re missing pieces of the puzzle in our theories and have an incomplete understanding of our universe,” says Hayden. “Laser cooling will enable much more precise comparisons between matter and antimatter atoms, and this will in turn provide clues to help figure out how the various pieces fit together.”

ALPHA is made up of researchers and students from institutions in 7 countries. ALPHA-Canada includes SFU, TRIUMF, UBC, the University of Calgary, and York University, along with contributors from the University of Victoria and BCIT.