Quantum mechanical and semi-classical treatment of quantum excitations due to the passage of a particle

We examine the validity of the approximation in which an α particle interacting with an atom is treated classically. In order to analyse such interactions, we perform a model simulation in which the α particle is considered as a particle in one dimension, and the atom as a quantum two-level system. The particle impinges on and excites the two-level system. We treat the particle in two ways: as a quantum mechanical wave packet, and as a …