Monday, December 16, 2013
4:00 pm
East Bridge 114

CMP Seminar

Preparing and preserving low entropy states in optical lattices
Stephan Langer, Postdoctoral Fellow, University of Pittsburgh

Experiments with ultra-cold atoms in optical lattices present a unique way to study strongly interacting many-body quantum systems, in a microscopically well-understood environment. Over the course of the last decade these models have successfully emulated the paradigm models of condensed matter physics, e.g., the Hubbard model. A key challenge to explore quantum phases of models that are candidates to exhibit quantum magnetism or superconductivity lies in the realization of sufficiently low temperatures and entropies. We here investigate this challenge from two complimentary points of view. On the one hand, is necessary to characterize and control competing heating processes in experiments with fermions. To this end we study the robustness of many-body states to spontaneous emissions in the framework of a many-body master equation for two-component fermions.

On the other hand we consider dynamical schemes to obtain low entropy ground states of strongly interacting many body systems. The focus here is on ultra-cold Bose and Fermi gases in bilayer optical lattice systems, a setup feasible with available experimental techniques. We are interested in regimes where the ground state of the coupled system consists of a Mott insulator in one layer and a superfluid/metallic state in the other layer that can serve as an entropy reservoir. For those we investigate the feasibility of adiabatic ramps and the emergence of characteristic many-body correlations as we change the energy offset and tunneling amplitude between the layers in real time.

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