Quantum Hall phase diagram of two-component Bose gases: Intercomponent entanglement and pseudopotentials

We study the ground-state phase diagram of two-dimensional two-component (or pseudospin-12) Bose gases in a high synthetic magnetic field in the space of the total filling factor and the ratio of the intercomponent coupling g↑↓ to the intracomponent one g>0. Using exact diagonalization, we find that when the intercomponent coupling is attractive (g↑↓<0), the product states of a pair of nearly uncorrelated quantum Hall states are remarkably robust and persist even when |g↑↓| is close to g. This contrasts with the case of an intercomponent repulsion, where a variety of spin-singlet quantum Hall states with high intercomponent entanglement emerge for g↑↓≈g. We interpret this marked dependence on the sign of g↑↓ in light of pseudopotentials on a sphere, and also explain recent numerical results in two-component Bose gases in mutually antiparallel magnetic fields where a qualitatively opposite dependence on the sign of g↑↓ is found. Our results thus unveil an intriguing connection between multicomponent quantum Hall systems and quantum spin Hall systems in minimal setups.