2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56505We will study the Klein-Gordon's field with an homogeneous external potential, which does not depend on $\h$. We will construct the Fock's space corresponding to our problem and we will see that there are phenomena of creation and anihilation of pairs particle-antiparticle. Finally, we will see that in dimension 1, when $\h\to 0$, these phenomena disappear. However, in dimension 2 or 3, when $\h\to 0$, the creation probability of particle-antiparticle pairs is not zero.11 pages, LateXMathematical Physicstext