  New effects of polarization multistability and polarization hysteresis in a
coherently driven polariton condensate in a semiconductor microcavity are
predicted and theoretically analyzed. The multistability arises due to
polarization-dependent polariton-polariton interactions and can be revealed in
polarization resolved photoluminescence experiments. The pumping power required
to observe this effect is of 4 orders of magnitude lower than the
characteristic pumping power in conventional bistable optical systems.
