From weakly to strongly correlated physics of bosons in the p band

by Dr Fernanda Pinheiro (Institute for Biological Physics, University of Cologne)

Wednesday 4 Sept 2013, 14:00 → 16:00 Europe/Stockholm

FA31

Following the experimental realization of optical lattices and numerous advances in manipulation and detection techniques, cold atoms in optical lattices have become a primary candidate for testing solid state and condensed matter models. Nowadays the physics of cold atoms is a rapidly evolving subject that brings together condensed matter, quantum information and quantum optics, forming a broad and interdisciplinary field of research. From the combination of state-of-the-art experiments with theoretical tools, cold atoms in optical lattices allow for investigation of a large number of questions of both theoretical and practical character. In this thesis, we explore the physics of bosonic atoms in the first excited band of an optical lattice - the p band. Due to the additional orbital degree of freedom, the physics in the p band is qualitatively different from the physics of the well characterized systems in the ground band. We will start by defining these orbital states for discussing properties of the system at the single particle level, and we follow by constructing a framework for characterizing mean-field properties of the many-body counterpart. Particular attention is given to the study of condensation in the p band of a confined system. After addressing questions at the mean-field level, we move to the strongly correlated regime. We show that under specific circumstances, the effective Hamiltonian describing the Mott phase with unit filling of bosons in the p band can be described by the spin-1/2 quantum XYZ Heisenberg model in an external field. Finally, we present extensions of this work that suggest the possibility of using p-orbital atoms for exploring the physics of spin chains beyond spin-1/2.