Photo CERN
Photo CERN


Antihydrogen is the antimatter equivalent of hydrogen, that is, it is the bound state of an antiproton and a positron. According to the so-called CPT theorem, the spectrum of antihydrogen should be identical to that of hydrogen. Antihydrogen should also fall at the same rate as ordinary hydrogen, if Einstein’s weak equivalence principle holds. A number of experiments at CERNs antiproton decelerator AD strive to test these fundamental symmetries. We are members of two of these collaborations:

ALPHA, which was the first experiment to trap antihydrogen atoms, as well as to make the first observation of the 1S-2S transition in antihydrogen, and the first measurement of its hyperfine spectrum. Stay tuned for more!

GBAR will be the first user of the new ELENA facility at CERN. GBAR will make and trap the antihydrogen ion (i.e., antiproton + 2 positrons), and then, after cooling, laser ionise it to study antimatter gravity as it falls.

Our contribution to both collaborations is mainly simulations and calculations of rates for various properties. Many of our results are also applicable to the growing area of antihydrogen research in general.

Another area of research is so-called Efimov states, made up of three ultracold atoms. Their existence was predicted already in 1970 by Vitali Efimov, but it took until 2006 before they were confirmed experimentally, using Cs atoms. One reason for the interest in these states is that according to their quantum theory they exhibit universal properties, i.e. properties independent of the physical system used to realise them. Thus, they could appear not only in various atomic systems, but in any physical system, provided that the conditions are right. Efimov states are also an example of strongly (or resonantly) interacting systems, which is of interest in many areas of physics.