Movie S2.

Correlated electron–photon propagation with factorizable initial state: Initially the electron populates the electronic ground state, and the photon field populates a superposition state between the vacuum and the one-photon state. Upper Left shows the exact (black) and classical (red) dipole moment. Lower Left shows the evolution of the Mandel Q(t) parameter and purity γ(t) for exact (black) and classical approximation (red). Upper Right shows the exact mean-field exchange correlation vMxc(r,t) potential and Lower Right shows the corresponding electronic density.