Framework Constructs Momentum States; Coupling Links Two Dimensions for Symmetry

Permissible momenta aren’t what they seem: new work reveals that allowed movement directions within two-dimensional quantum systems can be fundamentally restricted by motion *perpendicular* to them. This advances real-space exact diagonalization with a unified construction protocol clarifying how stabilizer subgroup structure dictates varying dimensions of cyclic subspaces, a key step for accurate simulations. The result prevents errors arising from incomplete calculations when modelling complex many-body scenarios like topological states and localization phenomena.