Research NewsQuantum Mechanics

Physicists Trap Photons and Count Them One by One

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Science  05 Apr 1996:
Vol. 272, Issue 5258, pp. 34
DOI: 10.1126/science.272.5258.34


Physicists know that light is made of packets called photons, but they have longed to actually see light's discrete nature. Now they can, in an ingenious experiment at the Ecole Normale Supérieure in Paris that captures a few photons in a tiny chamber and counts them like marbles. Along with painstaking engineering, the experiment required a supersensitive scheme for detecting photons: individual atoms, crossing the chamber one by one in an excited state that is sensitive to the presence of the photons.