Subtle is the atom, but malicious it is not. This paraphrase of Einstein's famous remark aptly summarizes the work reported by Ourjoumtsev et al.1 on page 623 of this issue. Subtle, because the atom is a quantum object that can, in principle, produce quantum light — the most immediate example being the emission of a single photon. There is a great deal beyond single photons, however: the work of the past 50 years has brought many quantum subtleties to our awareness, thus creating the field of quantum information and the quest for a quantum computer. As for malice, the atom bears none, because, as the authors demonstrate, even its most guarded subtlety, hidden for 30 years, can nevertheless be revealed by the resolute.
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