Precise Measurement of Antihydrogen hyperfine splitting

Researchers at the ALPHA experiment at CERN have published a new paper that reports a 100-fold improvement in precision when they measured antihydrogen's hyperfine splitting.

Dr. Mike Hayden, Distinguished Professor Emeritus at SFU Physics and a collaborator at the ALPHA experiment, was a major contributor to this experiment.  Using various breakthroughs such as a new antihydrogen trapping technique, the team upgraded their precision from 400 parts per million (in 2017) to 4 parts per million.

This measurement of the tiny energy splitting in antihydrogen appeared to match those observed with regular hydrogen, giving strong support to the theorem that predicts matter and antimatter should exhibit perfect symmetry (known as CPT symmetry).

See the APS news article on the experiment and the full paper on Nature.