> To go smoothly from 0 to 1, the system transitions through a series of superpositions of both states, i.e. it starts out entirely in state 0, and then transitions smoothly to being mostly in state 0 and a little bit in state 1, to being half in each state, to being mostly in 1 and a little bit in 0, to being entirely in 1.
Not really. An atom can be described by its quantum state only if it's isolated and in that case its energy is constant. If the states s_1 and s_2 have different energies E_1 and E_2 then the quantum state may be a superposition of the states s_1 and s_2 with an expected value for the energy between E_1 and E_2 but no "smooth transition" is possible.
For the transition to happen the atom has to be coupled with an external field. One way to think of it is as the evolution of the system composed of the atom plus a photon, where the transition between the states "excited atom and no emitted photon" and "unexcited atom and emited photon" happens at constant energy.
Not really. An atom can be described by its quantum state only if it's isolated and in that case its energy is constant. If the states s_1 and s_2 have different energies E_1 and E_2 then the quantum state may be a superposition of the states s_1 and s_2 with an expected value for the energy between E_1 and E_2 but no "smooth transition" is possible.
For the transition to happen the atom has to be coupled with an external field. One way to think of it is as the evolution of the system composed of the atom plus a photon, where the transition between the states "excited atom and no emitted photon" and "unexcited atom and emited photon" happens at constant energy.
Edit: See https://en.m.wikipedia.org/wiki/Spontaneous_emission#Theory