Testing Fundamental Symmetries with Antihydrogen
One of the central goals of antimatter research is to compare the properties of antimatter with those of matter to an extremely high precision. The CPT (Charge, Parity, Time) symmetry theorem, a cornerstone of the Standard Model, predicts that an antimatter atom should have the exact same energy levels as its matter counterpart. Our research focuses on testing this prediction by performing high-precision laser spectroscopy on trapped antihydrogen atoms.
Antihydrogen Spectroscopy
We probe the 1S-2S transition in antihydrogen. This transition is exceptionally narrow, allowing for incredibly precise measurements. By exciting antihydrogen atoms with a laser at a specific frequency (243 nm) and comparing the result to the well-known value for hydrogen, we can detect even minute deviations that would signal new physics beyond the Standard Model.
So far, experiments like ALPHA at CERN have found the frequencies to be identical within an experimental precision of a few parts in a trillion, providing a stringent test of CPT symmetry.
Gravitational Interaction of Antimatter
Does antimatter fall up or down? According to Einstein's weak equivalence principle, gravity should affect antimatter in the same way it affects matter. However, this has never been directly observed. Experiments such as ALPHA-g, AEgIS, and GBAR are designed to measure the effect of Earth's gravitational field on antihydrogen atoms. The ALPHA collaboration recently published the first direct observation, confirming that antimatter does indeed fall downwards, consistent with theory.
Future goals are to improve the precision of this measurement to search for subtle differences that could point to new quantum theories of gravity.
Advanced Confinement and Cooling
Progress in antimatter research is intrinsically linked to our ability to create, trap, and cool antimatter. Our efforts are focused on:
- Developing Hybrid Traps: Combining magnetic minimum traps (for neutral antihydrogen) with Penning traps (for charged constituents) to improve trapping efficiency.
- Laser Cooling: Implementing laser cooling techniques for antihydrogen, a significant challenge that, if successful, would dramatically increase measurement precision by reducing the thermal motion of the trapped atoms.
- Transportable Traps: Designing portable antimatter traps like BASE-STEP to move antimatter from the production facility (like CERN's AD) to other, more specialized experimental environments.