Antihydrogen-testbench for the symmetry of the antiworld

摘要

Comprising an antiproton and a positron, antihydrogen is the simplest atom of antimatter. The transition frequency of 2.466 X 10~15 Hz from the 1S ground state to the 2S metastable state, if measured with the accuracy set by the natural line width of 1.1 Hz, offers the chance to test CPT invariance and the equivalence principle.