ABSTRACT
The Hamiltonians of the particle HP and radiation HR commute and thus have a common set of eigenvectors. These are given as the
tensor product of the electronic state |a〉 and the eigenstates |nl〉 of the electromagnetic modes:
|φ〉 = |a〉 ⊗ |n1〉 ⊗ · · · ⊗ |nl〉 ⊗ . . . = |a, n1, . . . , nl . . .〉 . (4.1)
In this section on light-matter interaction the Hamiltonian HI is treated as a perturbation on these eigenstates |φ〉. Under the influence of this perturbation the states |φ〉 are no longer eigenstates and thus get explicitly time dependent. This results in a
plethora of phenomena, like absorption, spontaneous emission, Rabi
oscillations, and many more.
