Ultracold Bosons on a Regular Spherical Mesh

I study the zero-temperature phase behavior of bosonic particles living on the nodes of a regular spherical mesh (Platonic mesh) and interacting through an extended Bose-Hubbard Hamiltonian. Only the hard-core version of the model is considered here, for two instances of Platonic mesh. Using the mean-field decoupling approximation, I show that the system may exist in various ground states, which can be regarded as analogs of gas, solid, supersolid, and superfluid. For one mesh, by comparing the theoretical results with the outcome of numerical diagonalization, I manage to uncover the signatures of diagonal and off-diagonal spatial orders in a finite quantum system.