Superconductivity in strongly repulsive fermions: the role of kinetic-energy frustration.

We discuss a physical mechanism of a non-BCS nature which can stabilize a superconducting state in a strongly repulsive electronic system. By considering the two-dimensional Hubbard model with spatially modulated electron hoppings, we demonstrate how kinetic-energy frustration can lead to robust d-wave superconductivity at arbitrarily large on-site repulsion. This phenomenon should be observable in experiments using fermionic atoms, e.g. 40K, in specially prepared optical lattices.