This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For the first time, Northwestern University physicists have coaxed a single positron—the antimatter counterpart of an electron—into an exquisitely controlled quantum state. After capturing the fast-moving particle from radioactive decay, the scientists cooled it to nearly absolute zero.
Then, they suspended the particle in a near-perfect vacuum, preventing it from touching ordinary matter—an encounter that would cause it to vanish. By trapping and cooling a positron this way, the scientists created what they call a "one-positron quantum cyclotron." In this state, the positron essentially behaves much like an artificial atom with quantum energy levels scientists can precisely control and observe. The advance ultimately could enable the most precise test yet of a fundamental symmetry between electrons and their antimatter counterparts.
According to the Standard Model of particle physics, electrons and positrons should be nearly perfect mirror images of one another. By measuring the positron's magnetic properties with unprecedented precision and comparing those to the electron's properties, physicists could put this fundamental symmetry to its most stringent test yet. If the measurements don't match as expected, they would reveal a crack in the Standard Model, offering new clues to enduring mysteries, including why ordinary matter, rather than antimatter, dominates the universe.
"Antimatter gets its popular charm from science fiction," said Northwestern's Gerald Gabrielse, who led the study published in Physical Review Letters. "If you take an electron and an anti-electron (or positron) and collide them together, they both disappear. We describe that as annihilation, a concept that fuels science fiction writers' imaginations.
"The big mystery of the universe is that the Big Bang should have created equal amounts of matter and antimatter. But, if that were true, it would annihilate, and we'd be left with nothing. There's clearly something wrong with that theory, and that's what we're trying to figure out." Gabrielse is the Board of Trustees Professor of Physics at Northwestern's Weinberg College of Arts and Sciences, where he directs the Center for Fundamental Physics.
Thomas Myers, a doctoral student in Gabrielse's laboratory, is the paper's first author. A longstanding theory, the Standard Model describes the fundamental particles and three of the four fundamental forces (electromagnetic, strong nuclear and weak nuclear forces) in the universe. Experiment after experiment has confirmed the model's predictions with extraordinary precision.
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