On the possibility of acousto-optic control of spin states of a polariton condensate

The spin properties of a condensate of exciton polaritons under resonance optical excitation are considered. It is shown theoretically that the average spin of the condensate depends on the difference between the frequencies of the polariton level and the external pump. This fact opens the possibility to control the spin states of the polariton condensate by changing the exciton frequency by means of the excitation of acoustic waves in the microcavity. In particular, it is predicted that, in laterally anisotropic systems, at fixed intensity and polarization of the pump wave, switches between the condensate states with linear, right-, and left-circular polarizations are possible on a picosecond time scale, leading to equally rapid changes in the polarization of the transmitted light.