Controlling Spin Exchange Interactions of Ultracold Atoms in Optical Lattices:
We describe a general technique that allows one to induce and control strong interaction between spin states of neighboring atoms in an optical lattice. We show that the properties of spin exchange interactions, such as magnitude, sign, and anisotropy, can be designed by adjusting the optical potentials.We illustrate how this technique can be used to efficiently ‘‘engineer’’ quantum spin systems with desired properties, for specific examples ranging from scalable quantum computation to probing a model with complex topological order that supports exotic anyonic excitations.
Generation and Detection of Atomic Spin Entanglement in Optical Lattices:
Ultracold atoms in optical lattices oer a great promise to generate entangled states for scalable quantum information processing owing to the inherited long coherence time and controllability over a large number of particles. We report on the generation, manipulation and detection of atomic spin entanglement in an optical superlattice. Employing a spin-dependent superlattice, atomic spins in the left or right sites can be individually addressed and coherently manipulated by microwave pulses with near unitary delities. Spin entanglement of the two atoms in the double wells of the superlattice is generated via dynamical evolution governed by spin superexchange. By observing collisional atom loss with in-situ absorption imaging we measure spin correlations of atoms inside the double wells and obtain the lower boundary of entanglement delity as 0.790.06, and the violation of a Bell's inequality with S=2.210.08. The above results represent an essential step towards scalable quantum computation with ultracold atoms in optical lattices.