  We have numerically obtained theoretical results for the collapse and the
revival of the quantum Rabi oscillations for low average number of coherent
photons injected on a two-level system in a lossy resonant cavity. We have
adopted the multimode Jaynes-Cummings model for the same and especially treated
the ``Ohmic" loss to the walls of the cavity, the leakage from the cavity, and
the loss due to the spontaneous emission through the open surface of the
cavity. We have compared our results with the experimental data obtained by
Brune et al [Phys. Rev. Lett. 76, 1800 (1996)] in this regard.
