Evidence of a spin liquid with hard-core bosons in a square lattice

We show that laser-assisted hopping of hard-core bosons in a square optical lattice can be described by an antiferromagnetic J 1 ‚Äì J 2 XY model with a tunable ratio of J 2 / J 1 . We numerically investigated the phase diagram of the J 1 ‚Äì J 2 XY model using both the tensor network algorithm for infinite systems and the exact diagonalization for small clusters and found strong evidence that in the intermediate region around J 2 / J 1¬†‚à º¬†0.5, there is a spin liquid phase with vanishing magnetization and valence bond orders, which interconnects the N√©el state on the J 2¬†‚♬†J 1 side and the stripe antiferromagnetic phase on the J 2¬†‚â´¬†J 1 side. This finding opens up the possibility of studying the exotic spin liquid phase in a realistic experimental system using ultracold atoms in an optical lattice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98625/1/1367-2630_14_11_113039.pd