The second ingredient that is needed to create antihydrogen are antiprotons. The Antiproton, p, is the antimatter counterpart of a proton. Antiprotons can be produced in collisions involving cosmic rays, but do not occur on earth naturally. That’s why we need to produce them with the accelerators at CERN.
Once you've trapped antihydrogen what do you do? You measure it!
We report the first resonant quantum transitions in antihydrogen atoms.