Abstract
In the previous lecture, we explained the physical origin of the interaction potential between two neutral atoms, and gave the orders of magnitude in energy and distance that characterize it. We now turn to the tools that will enable us to quantitatively treat the collision between two atoms under the effect of this potential. In this chapter, we'll introduce the general formalism known as diffusion theory, before concentrating in the next chapter on the case of low-energy collisions that govern quantum gas physics.
