Séminaire de groupe
|Quantum lattice systems via the 1/Z expansion|
|jeudi 11 avril 2013 , 14h00|
|Salle de séminaire du groupe de Physique Statistique|
Quantum lattice systems are encountered in many field of physics: material sciences, ultracold gas and quantum optics. The typical examples are the Fermi Hubbard models or the Heisenberg spin model. In this talk, we investigate these lattice systems from a general point of view using the 1/Z expansion method where Z is the coordination number. This method provides a general framework of hierachical equations for n-sites reduced density matrices allowing to systematically determine the equilibrium properties such as the ground states but also to describe the non equilibrium dynamics. We illustrate the powerfulness of these general concepts for several examples (quantum fluctuations, sweeping through a quantum transition or Sauter-Schwinger effect) in the Mott phase of the Bose and Fermi Hubbard models or the Heisenberg model and compare our findings with the results found in the literature.