Researchers in the ALPHA collaboration at CERN have, for the first time, successfully cooled antihydrogen atoms with laser light. Antihydrogen is the simplest form of anti-atomic matter, and the technology known as laser cooling was first demonstrated four decades ago in ordinary matter. Laser cooling is commonly used in many areas of research.
The The first application From laser cooling to antihydrogen it opens the door to more accurate measurements of the internal structure of antihydrogen and how it behaves under the influence of gravity. Comparing the measurements with those of normal hydrogen atoms may reveal differences between matter and antimatter atoms. These differences, if they exist, could help researchers determine why the universe is made of only matter, an imbalance known as matter and antimatter asymmetry.
The researchers on the project say the ability to cool antihydrogen atoms with a laser is a change factor for spectroscopy and gravitational measurements. The new capability could lead to new perspectives in antimatter research, including the creation of antimatter particles and the development of antimatter interferometry. Alpha spokesman Jeffrey Hangst says cooling of antimatter with a laser has been science fiction about a decade ago.
The team created antihydrogen atoms but took antiprotons from the CERN Antiproton Decelerator and attached them to positrons emerging from the sodium source 22. The produced antihydrogen atoms were trapped inside a magnetic trap that prevented them from coming into contact with the substance. The researchers say that measuring the behavior of antihydrogen within the Earth’s gravitational field is limited by kinetic energy or, equivalently, the temperature of anti-atoms.
Laser cooling helps control the temperature of the antiatoms. Anti-atoms absorb the laser’s photons, making them reach a higher energy state. Then they emit photons and spontaneously decay to their initial state. The reaction depends on the velocity of the atoms, and since the photons give off momentum, the repetition of the absorption and emission cycle causes the atoms to cool to a lower temperature.