Enlarged symmetry and coherence in arrays of quantum dots

Enlarged symmetry characterized by the group SU(4) can be realized in isolated semiconducting quantum dots. A Hubbard model then describes a pillar array of coupled dots, and at half-filling the system can be mapped onto an SU(4) spin chain. The physics of these structures is rich as novel phases are attainable. The spins spontaneously dimerize, and this state is robust to perturbations that break SU(4) symmetry. We propose ways to experimentally verify the existence of the dimerized phase.