Abstract

We report on the observation of short-range quantum magnetic correlations of fermionic atoms in an optical lattice. The key to entering the regime of quantum magnetism is a tunable geometry optical lattice, which allows us to locally redistribute the entropy. When loading a low-temperature two-component gas with repulsive interactions into either a dimerized or anisotropic simple cubic lattice, we find magnetic correlations on neighbouring sites. The correlations manifest as an excess number of singlets as compared to triplets consisting of two atoms with opposite spins. For the anisotropic lattice, we determine the transverse spin correlator from the singlet-triplet imbalance and observe antiferromagnetic correlations along one spatial axis. I will further report on experiments in which we have created cold-atom analogues of mesoscopic conductors and superconductors