Excitation of a d-Density wave in an optical lattice with driven tunneling.

Quantum phases with unusual symmetries may play a key role in the understanding of solid state systems at low temperatures. We propose a realistic scenario, well in reach of present experimental techniques, which should permit us to produce a stationary quantum state with d x2-y2 symmetry in a two-dimensional bosonic optical square lattice. This state, characterized by alternating rotational flux in each plaquette, arises from driven tunneling implemented by a stimulated Raman scattering process. We discuss bosons in a square lattice; however, more complex systems involving other lattice geometries appear possible.