2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203499It is shown that response properties of a quantum harmonic oscillator are in essence those of a classical oscillator, and that, paradoxical as it may be, these classical properties underlie all quantum dynamical properties of the system. The results are extended to non-interacting bosonic fields, both neutral and charged.Accepted to Annals of PhysicsQuantum PhysicsStatistical MechanicsMathematical Physicstext