2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/150933This paper has been withdrawn, as the explicit form of the propagator can be found in: V.V.Dodonov, I.A.Malkin and V.I.Man'ko, J.Phys.A 8 (1975) L19 V.V.Dodonov, I.A.Malkin and V.I.Man'ko, Int.J.Theor.Phys. 14 (1975) 37, Sec.3 V.V.Dodonov, I.A.Malkin and V.I.Man'ko, Theor.Math.Phys. 24 (1975) 746, Sec.2 I am grateful to Professor Victor Dodonov for bringing this to my attention.Paper withdrawnQuantum Physicstext