For a long time most atomic physicists were trained in accordance with 1981 Nobel laureate Arthur Schawlow’s dictum, “A diatomic molecule is a molecule with one atom too many.” Compared with atoms, even the simplest molecules seem dauntingly complicated. Their internal vibrational and rotational (collectively called “rovibrational”) motions and their lack of spherical symmetry introduce structural features completely absent in atoms. That complexity makes the quantum mechanical properties of molecules far more difficult to manipulate, control, and measure than in their simpler atomic counterparts. Nevertheless, during the past several years, physicists have begun to work with molecules in high-precision experiments designed to probe some of the most fundamental features of physical law.
Such precision measurements have long played an important role in atomic physics. For example, experiments have looked for violations of spatial-inversion symmetry, or parity (P), to investigate the possible existence of new particles analogous to the...
