  The Berry phase (BP) in a quantized light field demonstrated more than a
decade ago (Phys. Rev. Lett. 89, 220404) has attracted considerable attentions,
since it plays an important role in the cavity quantum electrodynamics.
However, it is argued in a recent paper ( Phys. Rev. Lett. 108, 033601) that
such a BP is just due to the rotating wave approximation (RWA) and the relevant
BP should vanish beyond this approximation. Based on a consistent analysis we
conclude in this letter that the BP in a generic Rabi model actually exists, no
matter whether the RWA is applied. The existence of BP is also generalized to a
three-level atom in the quantized cavity field.
