Controlling and Detecting Spin Correlations of Ultracold Atoms in Optical lattices

TL;DR

This paper demonstrates a method to control and detect spin correlations in ultracold atoms within optical lattices, enabling studies of quantum magnetism and the creation of multi-particle entangled states.

Contribution

It introduces a new technique using a bichromatic superlattice to measure and manipulate spin correlations, including singlet-triplet coupling and bond-length extension via SWAP operations.

Findings

Successful creation of valence bond states with ultracold atoms.

Coherent coupling between singlet and triplet states demonstrated.

Potential for scalable entangled state generation in optical lattices.

Abstract

We report on the controlled creation of a valence bond state of delocalized effective-spin singlet and triplet dimers by means of a bichromatic optical superlattice. We demonstrate a coherent coupling between the singlet and triplet states and show how the superlattice can be employed to measure the singlet-fraction employing a spin blockade effect. Our method provides a reliable way to detect and control nearest-neighbor spin correlations in many-body systems of ultracold atoms. Being able to measure these correlations is an important ingredient to study quantum magnetism in optical lattices. We furthermore employ a SWAP operation between atoms being part of different triplets, thus effectively increasing their bond-length. Such SWAP operation provides an important step towards the massively parallel creation of a multi-particle entangled state in the lattice.