Scientists Successfully Laser-cooled Positronium Ions For The First Time!

In a recent study, the AEgIS system under the European Center for Nuclear Research (CERN) successfully laser-cooled positronium ions, taking an important step toward a matter-antimatter system that emits laser-like gamma rays.
The results of this experiment not only provide strong support for high-precision testing of whether antimatter and matter fall to Earth in the same way, but also pave the way for a whole new range of antimatter research, including the possibility of producing gamma-ray lasers.
The Aegis System (AEgIS) is one of several experiments producing and studying anti-hydrogen atoms at CERN's Antimatter Factory, whose goal is to test with high precision whether antimatter and matter both fall to Earth in the same way.
In a paper recently published in Physical Review Letters, the AEgIS collaboration reports on an experimental feat that not only helps to achieve this goal, but also paves the way for a whole new range of antimatter research, including the prospect of producing gamma-ray lasers, which would allow researchers to see into the nucleus of an atom inside and have applications beyond physics.
The goal of AEgIS, one of several experiments at CERN's Antimatter Factory, is to study the properties of anti-hydrogen atoms. To create anti-hydrogen (a positron spinning around an antiproton), AEgIS directs a beam of positrons (an electron spinning around a positron) into a cloud of antiprotons created and decelerated by the Antimatter Factory. When an antiproton and a positron meet in the antiproton cloud, the positron gives up its positron to the antiproton, resulting in the formation of anti-hydrogen.
This process allows AEgIS to study positron, an antimatter system that is of interest because it contains only two point particles - the electron and its antimatter.
However, the positron has an extremely short lifetime of 142 billionths of a second and subsequently annihilates into gamma rays. To study this short-lived particle, the AEgIS team successfully applied laser cooling techniques to a sample of positrons.
This is a feat accomplished by the AEgIS team. By applying laser cooling to a positron sample, they succeeded in reducing the temperature of the sample from 380 degrees Celsius to 170 degrees Celsius, a reduction of more than half. This feat provides a solid foundation for subsequent experiments, and the team aims to further reduce the temperature to below 10 Kelvin.
The success of laser-cooled positrons opens up new possibilities for antimatter research. First, it has made possible high-precision measurements of matter-antimatter systems, helping to reveal new physics. Second, the technique has also enabled researchers to produce positronic Bose-Einstein condensates, which are condensates in which all components occupy the same quantum state. Such condensates are thought to be candidates for generating coherent gamma-ray light, which is expected to provide researchers with a peek inside atomic nuclei.
"If the Bose-Einstein condensate of antimatter is able to produce coherent gamma-ray light, it will be an immensely powerful tool in the field of basic and applied research, allowing researchers to gain insight into the mysteries of atomic nuclei." Ruggero Caravita said.
Recall that laser cooling technology was first applied to antimatter atoms three years ago. The core principle lies in the gradual slowing down of atoms through a cyclic process of photon absorption and emission, which is mainly realized by narrow-band lasers that emit light in a small frequency range. However, the AEgIS team used a unique broadband laser technology in their research.
Ruggero Caravita further explains, "The advantage of the broadband laser technique is that it can effectively cool not only a small sample of positrons, but also a much larger sample of positrons. In addition, we did not use any external electric or magnetic fields during the experiment, which not only simplifies the experimental setup but also extends the lifetime of the positrons."
The AEgIS Collaboration has shared its research results on positron laser cooling with independent teams using different techniques, and on the same day posted this important result on the arXiv preprint server for the reference and information of researchers worldwide.