For the first time, physicists have observed in photons one of the weirdest and most basic phenomena in quantum mechanics: that field of physics where subatomic objects follow strange, unfamiliar laws. In the quantum world, particles like photons spend most of their time in a bizarre condition called a superposition, meaning the particles exist in several possible states at once. The superposition collapses into one of its component states only when the particle is measured. Amazingly, physicist Serge Haroche and his team at École Normale Supérieure in Paris reported in August that they were able to watch the process of this collapse as it happened in a photon, one of the most difficult—and most useful—particles to work with in experimental physics.
The physicists used a variant of a complicated method for measuring photons they had first devised in 1999—the only existing way to count photons without destroying them in the ...
