GS Paper III

News Excerpt:

Recently, an international team of physicists from the Anti-hydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration has achieved a breakthrough by demonstrating the laser cooling of Positronium.

What is Positron:

• Positronium, comprising a bound electron ( e-) and positron ( e+), is a fundamental atomic system. 
• Due to its very short life, it annihilates with a half life of 142 nano-seconds. 
• Its mass is twice the electron mass and enjoys the unique distinction of being a pure leptonic atom. 

• This hydrogen-like system, with halved frequencies for excitation, makes it a great contender for attempting laser cooling and thereby performing tests of fundamental theories in physics. 

About the Experiment:

• The experiment was conducted by 19 European and one Indian research group comprising the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) collaboration.
• The experiment was performed at the European Organization for Nuclear Research, more popularly known as CERN, in Geneva. 
• This is an important precursor experiment to the formation of anti-Hydrogen and the measurement of Earth’s gravitational acceleration on antihydrogen in the AEgIS experiment.

• In addition, this scientific feat could open prospects to produce a gamma-ray laser that would eventually allow researchers to look inside the atomic nucleus and have applications beyond physics.
• This scientific achievement could open prospects to produce a gamma-ray laser that would eventually allow researchers to look inside the atomic nucleus and have applications beyond physics.

About the successfully conducted AEgIS experiment:

• During the past few years, several rounds of experimental runs were performed in an accelerator beam hall of the CERN before the AEgIS team tasted success.
• It was formally accepted as a scientific experiment by CERN in 2008, the setting up of the AEgIS experiment, its construction and commissioning continued through 2012 – 2016. 
• AEgIS comprised designing of the complex particle traps used to confine antiparticles, antiprotons and positrons. 
• In 2018, AEgIS became the first in the world to demonstrate the pulsed production of antihydrogen atoms.
• Experimentalists achieved laser cooling of Positronium atoms initially from ~380 Kelvin to ~170 Kelvin, and demonstrated the cooling in one dimension using a 70-nanosecond pulse of the alexandrite-based laser system. 
• The lasers deployed were either in the deep ultraviolet or in the infrared frequency bands.

Significance of the experiment:

• This experiment is expected to pave the way for performing spectroscopic comparisons required for Quantum Electrodynamics (QED).
• Quantum Electrodynamics (QED): It is a study of the light and its interaction with charged matter, and a possible degenerate gas of Positronium down the road.
• According to CERN, the new scientific development will allow high-precision measurements of the properties and gravitational behaviour of this exotic but simple matter–antimatter system, which could reveal newer physics. 
• It also allows the production of a positronium Bose–Einstein condensate, in which all constituents occupy the same quantum state.
• A Bose-Einstein condensate of antimatter would be an incredible tool for both fundamental and applied research, especially if it allowed the production of coherent gamma-ray light with which researchers could peer into the atomic nucleus.
• Such a condensate has been proposed as a candidate to produce coherent gamma-ray light via the matter-antimatter annihilation of its constituents; it would be a laser-like light made up of monochromatic waves that have a constant phase difference between them.

Conclusion:

The successful laser cooling of Positronium by the AEgIS collaboration marks a significant advancement in fundamental physics. This breakthrough not only opens the door to high-precision measurements in Quantum Electrodynamics but also paves the way for producing a positronium Bose-Einstein condensate, offering a powerful tool for both fundamental and applied research.