Correlated Spin-Flip Tunneling in a Fermi Lattice Gas

TL;DR

This paper demonstrates the experimental realization of density-dependent, correlated spin-flip tunneling in a fermionic lattice gas, revealing new insights into interaction-driven tunneling processes in quantum gases.

Contribution

It introduces a method to induce and spectroscopically resolve correlated spin-flip tunneling in a fermionic lattice, advancing understanding of interaction-dependent tunneling phenomena.

Findings

Correlated tunneling depends on neighboring site occupations.

Laser-induced processes generate doublons via light-assisted collisions.

Correlated tunneling is suppressed with vacancies in the lattice.

Abstract

We report the realization of correlated, density-dependent tunneling for fermionic 40K atoms trapped in an optical lattice. By appropriately tuning the frequency difference between a pair of Raman beams applied to a spin-polarized gas, simultaneous spin transitions and tunneling events are induced that depend on the relative occupations of neighboring lattice sites. Correlated spin-flip tunneling is spectroscopically resolved using gases prepared in opposite spin states, and the inferred Hubbard interaction energy is compared with a tight-binding prediction. We show that the laser-induced correlated tunneling process generates doublons via loss induced by light-assisted collisions. Furthermore, by controllably introducing vacancies to a spin-polarized gas, we demonstrate that correlated tunneling is suppressed when neighboring lattice sites are unoccupied.