Exact Chiral Spin Liquid from a non-Abelian Hofstadter Model 

We propose a series of fine-tuned Bose–Hubbard model endowed with a non-Abelian gauge potential that is directly implementable in cold-atom optical lattices . At half filling, the model maps to an effective spin Hamiltonian which, under the Matsubara–Matsuda transformation, becomes a hard-core-boson problem governed by a Kapit–Mueller–type Hamiltonian. The resulting strictly flat Chern band supports the exact lattice bosonic Laughlin state at filling factor ν=1/2. Consequently, magnetizing the spin system to the corresponding polarization stabilizes the exact Kalmeyer–Laughlin chiral spin liquid as the ground state of the microscopic model. This construction provides a rigorous and experimentally motivated route to realizing a chiral spin liquid from a controllable Hubbard platform, while sharpening the conceptual and practical connection between fractional Chern–insulator physics and quantum spin liquids.