Spontaneous spin bifurcations in a Bose-Einstein condensate of indirect excitons

In this paper, we theoretically study the spin dynamics of a spatially trapped Bose-Einstein condensate of indirect excitons (IXs). A spontaneous parity-symmetry breaking spin bifurcation for bright excitons is reported under non-resonant linearly polarized pumping. Above a certain pumping amplitude, condensation for bright excitons spontaneously and stochastically adopts one of two spin-polarized configurations Sz depending on initial occupations. This phenomenon of spontaneous spin bifurcations is attributed to the small energy splitting and difference in dissipation rates between bright and dark excitons in IX systems. The considered systems thus have potential applications in spin memories, spin switches and to simulate spin interactions in condensed lattices.