Stationary states of a trapped SU(3) spin-orbit-coupled Bose gas with soft-core interaction

We consider a SU(3) spin-orbit-coupled Bose gas with nonlocal soft-core interactions confined in a harmonic trapping potential. The presence of SU(3) spin-orbit coupling induces three minima of the single-particle spectrum. In the absence of spin-exchange interaction, our results show that regardless of the sign of the soft-core interaction, the ground state occupies one single minimum in the momentum space and corresponds to a threefold-degenerate magnetized phase. For the ferromagnetic condensate, the ground state shows an amplitude-modulated plane-wave state, where its modulated amplitude and frequency are related to the strength of the soft-core interaction and SU(3) spin-orbit coupling, respectively. In particular, due to the subtle balance of the soft-core interaction and SU(3) spin-orbit coupling, a stable higher-order spin vortex lattice can be formed in the lattice phase of an antiferromagnetic condensate, where the density distributions of each component and the total system show spatial configurations with threefold and sixfold symmetries, respectively. We also give an experimental protocol to observe such states within current experimental capacity.