March 31, 2021
Physics researchers achieve first-ever cooling of antimatter by laser
While the combination of antimatter and lasers sounds like the stuff of science fiction, researchers from the Faculty of Science at the University of Calgary are part of a research collaboration who have announced the world’s first laser-based manipulation of antimatter, using a Canadian-made laser system to cool a sample of antimatter down to near absolute zero.
The CERN-based ALPHA collaboration includes Dr. Robert Thompson, PhD, and Dr. Timothy Friesen, PhD, of the Department of Physics and Astronomy, along with graduate students Andrew Evans and Adam Powell.
Their achievement was published today — and featured on the cover — in the journal Nature, and is expected to significantly inform future antimatter research and inspire new experiments.
Novel technique to open doors to further antimatter experimentation
Antimatter is the enigmatic counterpart to matter. It exhibits near-identical characteristics and behaviours, but has the opposite electric charge. Because they annihilate when they come into contact with matter, antimatter atoms are exceptionally difficult to create and control, and had never before been cooled with a laser.
Thompson, who is also the University of Calgary’s associate vice-president (research) and director of Research Services, has been working on laser cooling applications in physics since the late 1980s. “At that time," he says, “we determined that the technology did not exist to achieve the laser cooling of hydrogen. Over three decades later, the technology has advanced to the point that this became possible, at least for the antimatter twin of hydrogen.”
“The reason why we want to make cold antimatter is that we’re trying to understand this fundamental question about the universe,” says Friesen. “According to our understanding, the Big Bang should have produced equal amounts of matter and antimatter. But when matter and antimatter meet, they annihilate and explode, and you get pure energy. Obviously that didn’t happen. We look out at the universe and see just matter.”
Big Bang mystery raises questions about antimatter
The laser cooling of antimatter opens the door to the next generation of antimatter experiments, which may help develop understanding of the fundamental symmetries of our universe, a set of rules for matter and energy which should be mirrored in antimatter if current models for physics are correct.
“In order to look really closely at antimatter, we need it to be very, very cold,” Friesen explains. “Our question is: is antimatter exactly the same as matter, or is there some small difference? With the new cold samples of antimatter that we produced, we hope to be able to answer some of these questions.”
The laser cooling technique may also open the door to the ability to create the world’s first antimolecules, antimatter clocks, and other antimatter-based innovations.
Discovery marks pivotal moment in decades-long research collaboration
Since its introduction 40 years ago, laser manipulation and cooling of ordinary atoms have revolutionized modern atomic physics and enabled several Nobel-winning experiments. The results in Nature mark the first instance of scientists applying these techniques to antimatter.
“It was a bit of a crazy dream to manipulate the motion of antimatter with a laser,” says Dr. Makoto Fujiwara, PhD, ALPHA-Canada spokesperson, TRIUMF scientist at the University of British Columbia (UBC), and the original proponent of the laser cooling idea. “I am thrilled that our dream has finally come true as a result of tremendous teamwork of both Canadian and international scientists.”
The ALPHA team also designed and constructed ALPHA-g, a vertical apparatus to measure whether dropped antimatter will fall exactly like matter in Earth’s gravity. The University of Calgary led that multinational Canada Foundation for Innovation (CFI) project, with about 80 per cent of the funding provided by Canada including contributions from provincial partners Alberta, British Columbia and Ontario.
Today’s reported results mark a watershed moment for ALPHA’s decades-long program of antimatter research, which began with the creation and trapping of antihydrogen for a world-record 1,000 seconds in 2011. The collaboration also provided a first glimpse of the antihydrogen spectrum in 2012, set guardrails confining the effect of gravity on antimatter in 2013, and showcased an antimatter counterpart to a key spectroscopic phenomenon in 2020.