Investigating superradiance in Bose-Einstein condensates, a team at Massachusetts Institute of Technology in Cambridge has reported that short pulses of laser radiation produce patterns of recoiling atoms different from longer pulses. The work, which appeared in the April 18 issue of Science, suggests that optical stimulation is the dominant process at early times.

Superradiance describes the collective emission of radiation from a macroscopic ensemble of atoms, such as a Bose-Einstein condensate. At short times, the researchers observed a previously unknown process, self-stimulated Kapitza-Dirac diffraction, which, they note, enables them to connect self-stimulated Bragg diffraction and matter-wave amplification, effects observed at longer time scales.