Topological superfluidity with repulsive fermionic atoms in optical superlattice

We present a novel route to fermionic superfluidity in repulsive systems, that employs local kinetic-energy fluctuations as a ``pairing glue'' between the fermions. In a system with two bands, one itinerant and one localized, we show how quantum fluctuations in the latter mediate an attractive interaction between the itinerant fermions. In the spin-polarized case, this mechanism gives rise to a topological $p$-wave superfluid state in 1D, and a chiral $p_x + {\rm i} p_y$ superfluid in 2D. We derive an effective low-energy model and demonstrate stability of these states against charge-density wave formation and phase separation. We also propose to observe this phenomenon with alkaline-earth atoms, e.g. ${\rm Yb}$ or ${\rm Sr}$, in an optical superlattice, and discuss several probes for characterizing the topological superfluid state, including momentum-resolved RF spectroscopy and an analog of the Edelstein magneto-electric effect.