Enhanced Superexchange in a Tilted Mott Insulator

TL;DR

This paper demonstrates how applying a tilt to a Mott insulator in an optical lattice suppresses tunneling but preserves spin transport, enabling control over superexchange interactions and studying pure spin dynamics.

Contribution

It introduces a method to tune superexchange rates and spin interactions in a tilted lattice, revealing new control over many-body spin systems.

Findings

Superexchange rates can be varied by over a factor of 100.

Tilt stabilizes larger systems with faster spin dynamics.

Defects become immobile, allowing pure spin dynamics studies.

Abstract

In an optical lattice entropy and mass transport by first-order tunneling is much faster than spin transport via superexchange. Here we show that adding a constant force (tilt) suppresses first-order tunneling, but not spin transport, realizing new features for spin Hamiltonians. Suppression of the superfluid transition can stabilize larger systems with faster spin dynamics. For the first time in a many-body spin system, we vary superexchange rates by over a factor of 100 and tune spin-spin interactions via the tilt. In a tilted lattice, defects are immobile and pure spin dynamics can be studied.