Manipulating antimatter with microwaves

By manipulating antihydrogen atoms with microwaves, scientists have provided the first glimpse of an anti-atomic fingerprint.

Researchers at CERN – led by a Canadian team – confined antiatoms in a magnetic trap and irradiated them with microwaves. Precise tuning of the microwave frequency and magnetic field enabled researchers to hit an internal resonance, kicking atoms out of the trap and revealing information about their properties.

“For decades scientists have wanted to study the intrinsic properties of antimatter atoms in the hope of finding clues that might help answer fundamental questions about our universe,” said Mike Hayden, a physicist with Simon Fraser University and a member of the ALPHA collaboration.

“In the middle of the last century, physicists were developing and using microwave techniques to study ordinary atoms like hydrogen. Now 60 or 70 years down the road, we have just witnessed the first-ever microwave interactions with an anti-atom.”

Hayden, together with colleague Walter Hardy, designed the apparatus used in this experiment, while another team in Vancouver teased faint signals from a sophisticated detector, pinpointing matter-antimatter annihilation events. Together, they have published their results in Nature.

“This study demonstrates the feasibility of applying microwave spectroscopy to fiendishly difficult-to-handle anti-atoms,” said Hardy, a physicist from the University of British Columbia. “ALPHA is about to enter an intensive upgrade phase that promises to create an ever clearer picture of the inner structure of anti-matter atoms.”

ALPHA is a collaboration of over 40 physicists from 15 institutions in Canada, Brazil, Denmark, Israel, Sweden, the UK and USA. Their main aim is the stable trapping of antihydrogen atoms to conduct experiments to study the fundamental symmetries between matter and antimatter.

“Hydrogen is the most abundant element in the universe, and we understand its structure extremely well,” said Jeffrey Hangst of Aarhus University, and spokesperson for the ALPHA collaboration. “Now we can finally begin to coax the truth out of antihydrogen. Are they different? Today, we can confidently say ‘time will tell’.”

• Nature