Quantum effects in cold collisions

Prerna Paliwal

J. Vigué

This paper discusses the effects of small interactions like hyperfine structure or Zeeman effect on ultra-cold collisions. These interactions are usually neglected during collisions, but it is shown here that they may have large dynamical consequences in the particular case of collisions of ultra-cold atoms interacting through the resonance dipole-dipole terms (proportional to r -3 , where r is the internuclear distance). These collisions involving an excited atomic pair are responsible for most of the escape processes in laser traps and a very interesting prospect is to reduce the escape rate through the use of external fields.

J. Weiner

Lambert Paul Parazzoli, Noah J. Fitch, Piotr Szymon Żuchowski +2 more

Controlling interactions between cold molecules using external fields can elucidate the role of quantum mechanics in molecular collisions. We create a new experimental platform in which ultracold rubidium atoms and cold ammonia molecules are separately trapped by magnetic and electric fields and then combined to study collisions. We observe inelastic processes that are faster than expected from earlier field-free calculations. We use quantum scattering calculations to show that electric fields can have a major effect on collision outcomes, even in the absence of dipole-dipole interactions.

J. Weiner

W. W. Smith

We review historical examples of coherent oscillatory effects in charge-exchange collisions or optical line emission (notably Rosenthal oscillations). The feasibility of using a cold-ion--neutral hybrid trap to observe Rosenthal oscillations is discussed.