Abstract
We predict the spontaneous symmetry breaking in a spinor Bose–Einstein condensate of exciton-polaritons (polaritons) caused by the coupling of its spin and orbital degrees of freedom. We study a polariton condensate trapped in a ring-shaped effective potential with a broken rotational symmetry. We propose a realistic scheme of generating controllable spinor azimuthal persistent currents of polaritons in the trap under the continuous wave optical pump. We propose a new type of half-quantum circulating states in a spinor system characterized by azimuthal currents in both circular polarizations and a vortex in only one of the polarizations. The spontaneous symmetry breaking in the spinor polariton condensate that consists in the switching from co-winding to opposite-winding currents in opposite spin states is revealed. It is characterized by the change of the average orbital angular momentum of the condensate from zero to non-zero values. The radial displacement of the pump spot and the polarization of the pump act as the control parameters. The considered system exhibits a fundamental similarity to a superconducting flux qubit, which makes it highly promising for applications in quantum computing.
Highlights
Reduction of the problem from two-dimensional to one-dimensional[36,37,38,39] enhances the role of nonlinearity induced by interactions and gives rise to various topological effects
It has been shown that breaking the symmetry itself does not lead to formation of azimuthal polariton currents
We have predicted the spontaneous symmetry breaking in the system of persistent azimuthal currents in the annular spinor exciton-polariton condensate under the effects of spin-orbit interaction (SOI) and particle-particle interactions
Summary
Reduction of the problem from two-dimensional to one-dimensional[36,37,38,39] enhances the role of nonlinearity induced by interactions and gives rise to various topological effects. In the |0 state, the phases of the circular polarization components of the polariton condensate makes a full turn around the pillar which results in the values of the winding numbers m∓ = ±1. The black drops in the distribution of the phases of the condensates in Fig. 2b illustrate the steady state polariton currents in the corresponding polarizations.
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