Crueltyfree: Counting photons without killing them

By Davide Castelvecchi, 15:57 PM April 15, 2008

Disclaimer: No particles were harmed in the making of this experiment. Physicists have found a way to count photons as they zip along, without destroying them. The researchers say that the technique will enable scientists to probe quantum effects that so far have been the subject only of speculation.

In physics labs, detecting light has long been synonymous with absorbing photons. Typically, the photons cease to exist and the light's energy transforms into an electrical signal. Physicists can...

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