Dynamical Casimir-Polder interaction between an atom and a real surface

We discuss the dynamical (i.e. time-dependent) Casimir-Polder force between a neutral atom and a real surface of arbitrary material, under non-equilibrium conditions. More specifically, we consider a polarisable neutral atom placed near a surface with arbitrary dielectric properties and we investigate the dynamical dressing and the consequent dynamical Casimir-Polder potential after the non-adiabatic (sudden) change of parameters involved in the atom-field coupling, such as the atomic transition frequency or the transition dipole moment. Using time-dependent perturbation theory and the matter-assisted field approach, we discuss how the physical properties of the real surface can influence the time dependence of the atom-wall Casimir-Polder potential, its intensity and sign, in different atom-wall distance regimes. We also show that the dynamical Casimir-Polder potential exhibits oscillations in time, yielding a transient repulsive force and that asymptotically settles to its stationary value. The physical relevance and the limits of validity of the results obtained are discussed.