Time-resolved Observation and Control of Superexchange Interactions with Ultracold Atoms in Optical Lattices

TL;DR

This study demonstrates the direct measurement and control of superexchange interactions in ultracold atoms within optical lattices, enabling switching between magnetic states and advancing quantum simulation capabilities.

Contribution

It provides the first direct measurement of superexchange interactions with ultracold atoms and introduces a method to dynamically control their magnitude and sign.

Findings

Measured superexchange interactions up to 1 kHz

Achieved control over interaction sign and strength

Confirmed theoretical predictions with additional corrections

Abstract

Quantum mechanical superexchange interactions form the basis of quantum magnetism in strongly correlated electronic media. We report on the direct measurement of superexchange interactions with ultracold atoms in optical lattices. After preparing a spin-mixture of ultracold atoms in an antiferromagnetically ordered state, we measure a coherent superexchange-mediated spin dynamics with coupling energies from 5 Hz up to 1 kHz. By dynamically modifying the potential bias between neighboring lattice sites, the magnitude and sign of the superexchange interaction can be controlled, thus allowing the system to be switched between antiferromagnetic or ferromagnetic spin interactions. We compare our findings to predictions of a two-site Bose-Hubbard model and find very good agreement, but are also able to identify corrections which can be explained by the inclusion of direct nearest-neighbor interactions.