Light does some weird math.
For one thing, quantum uncertainty means that a pulse doesn't necessarily have a well-defined number of photons. And acting on such a pulse may have counterintuitive consequences.
When Marco Bellini of the University of Florence in Italy and his collaborators used a laser to add a new photon to an existing light pulse, the pulse usually ended up with more photons, as expected. But when they subtracted a photon by passing a light pulse through a glass plate in such a way that a single photon bounced out, the pulse typically emerged with more photons rather than fewer. When the team performed the two operations in a row, the most likely number of photons in the pulse depended on the order in which the two operations were performed, the researchers report in the Sept. 28 Science.
Confirmation that the order of the operations of adding and subtracting a photon makes a difference to the outcome demonstrates a basic prediction of quantum theory.
"Although [this law] underlies the entire quantum behavior of light, it had never been checked directly," Bellini says.-D.C.
|Printer friendly Cite/link Email Feedback|
|Date:||Oct 13, 2007|
|Previous Article:||Antibiotic improves recovery from stroke.|
|Next Article:||Avoid Boring People: Lessons from a Life in Science.|
|A question of standards.|
|Zinc oxide revisited.|
|Spying vision cells: eye's motion detectors are finally found.|
|Math clubs get national sponsor.|
|Ray tracing: energetic cosmic rays linked to giant black holes.|