Northwestern University physicists trapped a single positron and cooled it to nearly absolute zero, creating a one-positron quantum cyclotron. The antimatter particle was held in a near-perfect vacuum for months.
The study, published in Physical Review Letters, gives Gerald Gabrielse and Thomas Myers a new platform for comparing positrons with electrons more precisely. Gabrielse said the team is trying to find where the Standard Model breaks down.
Gerald Gabrielse and Thomas Myers
Gabrielse, Northwestern’s Board of Trustees Professor of Physics, led the study. Myers, the paper’s first author, worked in Gabrielse’s laboratory. The group captured the fast-moving particle from radioactive decay, then cooled and isolated it until it behaved like an artificial atom with quantum energy levels scientists can control and observe.
That control is the point. The positron would vanish if it touched ordinary matter, so the vacuum and low temperature were essential to keeping it available for measurement.
Physical Review Letters
Gabrielse said, "Antimatter gets its popular charm from science fiction," and added, "If you take an electron and an anti-electron (or positron) and collide them together, they both disappear." He also said, "The big mystery of the universe is the Big Bang should have created equal amounts of matter and antimatter."
He continued, "There’s clearly something wrong with that theory, and that’s what we’re trying to figure out." The Standard Model describes the fundamental particles and three of the four fundamental forces in the universe, yet it cannot explain why the observable universe contains overwhelmingly more matter than antimatter.
Standard Model
The new cyclotron builds on earlier work Gabrielse said the team had already done with a single electron and with antiprotons. The next step is to use the positron’s magnetic properties for a more precise comparison with the electron, pushing toward a direct test of whether the two particles truly match in every measurable way.
How long the positron was actually trapped and what measurement results, if any, were already obtained are not stated. The published result leaves the method in place and the comparison ahead.
