  We propose a physical mechanism which enables permanent Rabi oscillations in
driven-dissipative condensates of exciton-polaritons in semiconductor
microcavities subjected to external magnetic fields. The method is based on
incoherent excitonic reservoir engineering. We demonstrate that permanent
non-decaying oscillations may appear due to the parity-time (PT) symmetry of
the coupled exciton-photon system realised in a specific regime of pumping to
the exciton state and depletion of the reservoir. For effective non-zero
exciton-photon detuning, permanent Rabi oscillations occur with unequal
amplitudes of exciton and photon components. Our predictions pave way to
realisation of integrated circuits based on exciton-polariton condensates.
