title: Controlling and detecting spin correlations of ultracold atoms 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 in studying quantum magnetism in optical lattices. We furthermore employ a SWAP operation between atoms which are part of different triplets, thus effectively increasing their bond-length. Such a SWAP operation provides an important step towards the massively parallel creation of a multiparticle entangled state in the lattice.
authors.affiliation: Fakultät für Physik, Ludwig-Maximilians-Universität, München, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Trotzky
authors.forename: Yu-Ao
authors.initials: YA
authors.lastname: Chen
authors.forename: Ute
authors.initials: U
authors.lastname: Schnorrberger
authors.forename: Patrick
authors.initials: P
authors.lastname: Cheinet
authors.forename: Immanuel
authors.initials: I
authors.lastname: Bloch