Absorption imaging of single atoms is reported in Nature Communications this week. The findings represent the maximum contrast available with this equipment, and the fast acquisition time demonstrated may enable rapid absorption imaging of single atom or molecular processes in cells.

Atoms and ions absorb light at certain wavelengths dictated by quantum mechanics, which also imposes a maximum rate of absorption for a particular atomic structure. David Kielpinksi and colleagues trapped single ions of the element ytterbium and shone light onto them resonant with an atomic absorption transition. They then recorded the light that was left on a detector, using a charge coupled device camera, effectively recording the shadow cast by the ion. The image contrast is at the limit of the experimental apparatus and agrees with the semiclassical theory used to describe atomic transitions.

Such experiments help confirm our understanding of atomic physics and may be useful for quantum computing.