Experiments in Cold and Ultracold Collisions

J. Weiner

Gerrit C. Groenenboom, Liesbeth M. C. Janssen

Weiner

J. Weiner

The subtle interplay between two-particle and particle–field interaction characterizes collision physics in the cold and ultracold kinetic energy regimes. Cross sections increasing by orders of magnitude and acute sensitivity to light-field intensity and polarization distinguish this new domain from conventional thermal environments. Early experiments are reviewed, and new results from collisions within optical traps and atomic beams are reported.

P. L. Gould

Daniel J. Heinzen, D. J. Wineland, Carl Wieman +1 more

Two recent developments in ultracold atomic collision physics are discussed. The first is the “optical shielding” of ultracold atomic collisions by optical radiation that is tuned to the blue of an atomic resonance. This radiation couples a pair of colliding atoms to repulsive excited states and prevents their close approach. This effect may substantially suppress inelastic collision rates, and is an interesting example of the control of a cold collision process by a weak perturbing field. The second topic is ultracold atom photoassociation spectroscopy. In this work, high resolution free‐bound absorption spectra are obtained which provide detailed information on the long‐range states of the two interacting atoms. The physics of these states has an appealing simplicity, and in addition is of importance for a complete understanding of the effects of atomic interactions in cold atom experiments. The photoassociation spectra also provide a unique probe of cold collisions.