Ultracold atoms in optical lattices can serve as versatile systems for exploring strongly interacting quantum phases in optical lattices. One of the major challenges of the field now lies in the realization of interactions between atoms with spins on neighbouring lattice sites, in order to observe quantum magnetic ordering phenomena in optical lattices. In my talk, I will show that we have recently been able to directly observe second order atom tunnelling of spinless atoms in optical lattices, which lies at the heart of quantum magnetism. An effective spin-spin superexchange interaction could then be directly detected between atoms with spin on neighbouring lattice sites, although no direct long range interaction is present between the underlying particles. This interaction can also be used to realize and detect robust entangled states with ultralong lifetimes, previously known from ion trap experiments.
10 Minute Talk: Phase-Sensitive Recombination of Two Bose-Einstein Condensates on an Atom Chip