Abstract:<p><pre><code>   We demonstrated interruptions of macroscopic duration in 
   a single trapped and cooled Ba+ ions’s 493‐nm 
   fluorescence. They are caused by transitions of the ion 
   into the ‘‘dark’’ 2D5&#x2F;2 state.—Multiple simultaneous 
   jumps of three ions indicate cooperative interaction 
   with the light.
</code></pre>
I haven&#x27;t read the paper but I&#x27;d be interested in a quote from the part that supports the statement: &quot;People do take photographs of single atoms. It requires a very colorful atom and a very bright flash,...&quot;<p>I&#x27;m not aware of a definition of atomic color but maybe that&#x27;s a real thing in analytical chemistry, spectroscopy or some other field. I wouldn&#x27;t be surprised.<p>Probably it&#x27;s just the wavelength of the emitted light.