Figure 1: Time evolution of the energy density in the periodically driven O(N) model.

The energy density ε(t) exhibits three distinct dynamical regimes: (I) At short times t, single-particle rearrangements lead to a fast increase of the energy density, up to times t_int at which interactions become relevant. (II) At intermediate times, t_int < t < t_th, a stable Floquet prethermal regime occurs in which the interacting system ceases to absorb. (III) At late times, beyond the thermalization time scale t > t_th, interactions between a large number of generated quasi-particle excitations cause strong heating. In that regime, the energy density displays an algebraic growth, , with an exponent that approaches for strong interactions. The data is shown for drive frequency Ω = 2.3 and for three different values of the interaction strength u, see legend.