Why in the News?

For the first time, 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 Positronium?

Positronium comprises a bound electron (e-) and a positron (e+), forming a fundamental atomic system.
What are its Properties?
- Concise (short) life where it annihilates with a half-life of 142 nanoseconds.
- Its mass is twice the electron mass, and it is considered a pure leptonic atom.
- Its hydrogen-like system, with halved frequencies for excitation, makes it ideal for attempting laser cooling and performing tests of fundamental physics theories.

Timeline: The AEgIS experiment was formally accepted by CERN in 2008, with construction and commissioning continuing through 2012-2016.
Team: Physicists representing 19 European and one Indian research group from the AEgIS collaboration announced this scientific breakthrough.
Experiment Location: The experiment was conducted at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland.
Why this is significant? This experiment serves as a crucial precursor to the formation of anti-hydrogen and the measurement of Earth’s gravitational acceleration on antihydrogen in the AEgIS experiment.

Temperature Reduction: Laser cooling initially brought Positronium atoms from ~380 Kelvin to ~170 Kelvin.
Laser System: A 70-nanosecond pulse of the alexandrite-based laser system was used to demonstrate cooling in one dimension.
Frequency Bands: Lasers deployed were either in the deep ultraviolet or infrared frequency bands.

Spectroscopic Comparisons: Physicists expect this experiment to pave the way for performing spectroscopic comparisons required for Quantum Electrodynamics (QED).
Potential Applications: The experiment allows for high-precision measurements of properties and gravitational behavior of Positronium, offering insights into newer physics and the production of a positronium Bose–Einstein condensate.