  Exciton-photon beats known as polariton Rabi oscillations in semiconductor
microcavities are usually excited by short pulses of light. We consider a
different pumping scheme, assuming a cw pumping of the Rabi oscillator from an
exciton reservoir. We account for the initial pulse of light setting the phase,
exciton decay due to exciton-phonon and exciton-exciton scattering, photon
leakage, and blueshift of the exciton resonance due to interactions. We find
non-trivial stationary solutions reminiscent of Kapitza pendulum, where
polaritons are accumulated at the upper branch while the lower branch empties.
