Quantum Magnetism and Topological Ordering via Rydberg Dressing near Förster Resonances.

We devise a cold-atom approach to realizing a broad range of bilinear quantum magnets. Our scheme is based on off-resonant single-photon excitation of Rydberg P states (Rydberg dressing), whose strong interactions are shown to yield controllable XYZ interactions between effective spins, represented by different atomic ground states. The distinctive features of Förster-resonant Rydberg atom interactions are exploited to enhance the effectiveness of Rydberg dressing and, thereby, yield large spin interactions that greatly exceed the corresponding decoherence rates. We illustrate the concept on a spin-1 chain implemented with cold rubidium atoms, and demonstrate that this permits the dynamical preparation of topological magnetic phases. Generally, the described approach provides a viable route to exploring quantum magnetism with dynamically tunable (an)isotropic interactions as well as variable space and spin dimensions in cold-atom experiments.