Chapter 2.6.3 - Ultra-Cold Collisions of Atoms and Molecules

Abstract

Collisions play a crucial role in cold atomic and molecular physics. They provide sources of loss and heating of trapped species and also provide opportunities for precision measurements and for control by magnetic, electric, or electromagnetic fields. Collisions are essential for thermalization in evaporative cooling, and they determine the properties of Bose–Einstein condensates. This chapter provides an overview of theory of cold atomic collisions. Low-energy collisions of neutral atoms or molecules in their electronic ground state are described by standard scattering theoretical methods in terms of well-characterized interatomic interactions. The special aspects of these collisions are due to the quantum threshold properties of the particular species involved. Scattering resonances play an important role in cold atom physics. Some can be tuned by external fields and used as precision spectroscopic probes of interatomic interactions. Tunable resonances can also be used to modify collisional properties, including the macroscopic properties of quantum degenerate gases.