2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125977Quantum physics involves an ensemble of quantum systems, usually one thinks of a large ensemble of identical quantum systems at one single time. In single ion experiments one has a single quantum system at an ensemble of different times. This provides the means of demonstrating the beginning of time of a semigroup evolution for a decaying state.pdfLaTeX with 1 latex-fig and 2 fig files in pdf; total 3 figsQuantum Physicstext