Nonresonant optical control of a spinor polariton condensate

We investigate the spin dynamics of polariton condensates spatially separated from and effectively confined by the pumping exciton reservoir. We obtain a strong correlation between the ellipticity of the non-resonant optical pump and the degree of circular polarisation (DCP) of the condensate at the onset of condensation. With increasing excitation density we observe a reversal of the DCP. The spin dynamics of the trapped condensate are described within the framework of the spinor complex Ginzburg-Landau equations in the Josephson regime, where the dynamics of the system are reduced to a current-driven Josephson junction. We show that the observed spin reversal is due to the interplay between an internal Josephson coupling effect and the detuning of the two projections of the spinor condensate via transition from a synchronised to a desynchronised regime. These results suggest that spinor polariton condensates can be controlled by tuning the non-resonant excitation density offering applications in electrically pumped polariton spin switches.P.G.L acknowledges support by the Engineering and Physical Sciences Research Council of UK through the Hybrid Polaritonics Programme Grant (EP/M025330/1). P.G.S. acknowledges funding from the EU Social Fund and Greek National Resources (EPEAEK II, HRAKLEITOS II), N.G.B acknowledges the financial support by Ministry of Education and Science of Russian Federation 1425320 (Project DOI: RFMEFI58114X0006). The authors acknowledge fruitful discussions with Prof. Alexey Kavokin and Dr Hamid Ohadi. The data from this paper can be obtained from the University of Southampton e-Print research repository.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by APS