A Superradiant Collision

A. Crubellier, Sylvain Liberman, Didier Mayou +1 more

An experiment performed on barium atoms has permitted us to observe an infrared emission whose spectral and temporal analysis has led us to identify it with collision-induced superradiance. Tentative theoretical interpretation is given in the dressed-atom formalism using the monochromatic approximation.

Michael S. Feld, J. C. MacGillivray

Xinyu Luo, Kuiyi Gao, L. Deng +2 more

We present experimental evidence supporting the postulation that the secondary effects of light-assisted collisions are the main reason that the superradiant light scattering efficiency in condensates is asymmetric with respect to the sign of the pump-laser detuning. Contrary to recent experimental study, however, we observe severe and comparable heating with all three pump-laser polarizations. We also perform two-color, double-pulse measurements to directly study the degradation of condensate coherence and the resulting impact on the superradiant scattering efficiency.

Richard Brito, Vítor Cardoso, Paolo Pani

Piotr Deuar, Jean-Christophe Jaskula, Marie Bonneau +4 more

We report the experimental realization of a single-species atomic four-wave mixing process with Bose-Einstein-condensate collisions for which the angular distribution of scattered atom pairs is not isotropic, despite the collisions being in the $s$-wave regime. Theoretical analysis indicates that this anomalous behavior can be explained by the anisotropic nature of the gain in the medium. There are two competing anisotropic processes: classical trajectory deflections due to the mean-field potential and Bose-enhanced scattering which bears similarity to superradiance. We analyze the relative importance of these processes in the dynamical buildup of the anisotropic density distribution of scattered atoms and compare the Bose enhancement effects to those in optically pumped superradiance.

Ian S. Osborne