  We show that the Casimir-Polder interaction may induce coherent oscillations
between degenerate atomic states. We illustrate this effect by computing the
Casimir-Polder induced Rabi frequency on a $^{87}$Rb atom as it interacts with
a reflecting surface. The atom oscillates between two Zeeman sublevels of its
ground state undergoing a periodic exchange of angular momentum with the vacuum
photons.
