Exotic atoms and molecules

A study reports on the observation of a new type of molecular bond between an ion and a Rydberg atom and characterizes the resulting molecule using an ion microscope study.

The spectral lines of antiprotonic helium atoms are shown to retain their sub-gigahertz linewidth upon submersion in a bath of superfluid helium, enabling the hyperfine structure to be resolved.

Multiple high-precision measurement campaigns at CERN of the antiproton-to-proton charge-to-mass ratio—to a precision of 16 parts per trillion—in a cryogenic multi-Penning trap offer no evidence of charge–parity–time violation, and set stringent limits on the clock-weak-equivalence principle.

The detailed structure of each atomic species determines what physics can be achieved with ultracold gases. This review discusses the exciting applications that follow from lanthanides’ complex electronic structure.

Positrons are key to the production of cold antihydrogen. Here the authors report the sympathetic cooling of positrons by interacting them with laser-cooled Be⁺ ions resulting in a three-fold reduction of the temperature of positrons for antihydrogen synthesis.