Fermionic superfluidity with repulsive alkaline-earth atoms in optical superlattices

We propose a novel route to superfluidity in fermionic alkaline-earth atoms with repulsive interactions, that uses local kinetic-energy fluctuations as a "pairing glue" between the fermions. We exploit different polarizabilities of electronic ${}^1 S_0$ ($g$) and ${}^3 P_0$ ($e$) states of the atoms to confine the $e$- and $g$- species in different optical superlattices. For example, in a one-dimensional case the $e$-lattice can be implemented as an array of weakly-coupled double-wells (DWs) with large intra-DW tunneling, and contain one localized $e$-atom in each DW to avoid losses due to $e$-$e$ collisions. On the contrary, the shallow $g$-lattice has a large bandwidth and an arbitrary filling. We consider a nuclear-spin polarized system and demonstrate how kinetic-energy fluctuations of the localized $e$-atoms mediate an attractive interaction between the $g$-fermions, thus leading to a $p$-wave superfluid. We derive a low-energy model and determine the stability of this state against charge-density wave formation and phase separation. Our results can be tested with ${\rm Yb}$ or ${\rm Sr}$ fermionic atoms and have a direct relevance for the physics of high-temperature superconductor materials.