Atom-surface forces using excited states have a host of compelling
applications, including repulsive and lateral forces. However, such states can
be fragile and difficult to prepare. Here we report an explicit normal-mode
based calculation of the Casimir-Polder potential between a ground-state atom
and a non-dispersive surface in the presence of an external quantised field.
The potential we derive shares some features with that of excited-state
Casimir-Polder forces even though we consider a ground-state atom. Our work
provides a physically transparent and intuitive picture of driven
Casimir-Polder potentials, as well as expanding on previous investigations by
providing analytic results that fully include retardation, as well as being
applicable for any choice of mutual alignment of the atom's dipole moment, the
external field, and the surface normal
