We consider theoretically phase-locking transition of ultra-cold neutral atoms trapped in optical lattice where the system can be realized as the array of individual Bose–Einstein condensates of elongated vertical and horizontal N rods in a wood-pile form. In this geometry every horizontal...

We have performed electronic spectral function calculations for the Hubbard model on the square lattice using recently developed quantum SU(2) × U(1) rotor approach that enables a self-consistent treatment of the antiferromagnetic state. The collective variables for charge and spin are isolated...