Ultracold quantum matter

Abstract:

The hydrogen atom is an important testing ground for fundamental physical theory, because it is the simplest stable atomic system and its properties can be calculated to enormous precision. Measurements on hydrogen played a major role in the development of quantum electrodynamics (QED), a theory of electromagnetic interactions which includes quantization of the radiation field1,2. Tests of QED in hydrogen involve precision measurements of transition frequencies; the transition generally studied is between two excited states (2s2S1/2 and 2p2P1/2). Much higher precision is possible if a transition involving the ground state is studied, but this potential has not so far been exploited because of experimental difficulties. We have now carried out an experiment of this type which has given preliminary results and opens new possibilities for precision tests of QED in the future. © 1987 Nature Publishing Group.