[Cnqo] Talk from Stephan Langer, Thursday 22nd, 3:00pm

[Andrew Daley]

Dear colleagues,

Next week, Stephan Langer (University of Pittsburgh) will visit us for four days at Strathclyde (Monday-Thursday). Stephan is a postdoctoral researcher who has been working with me in Pittsburgh on dynamics of cold atoms in optical lattices.

On Thursday 22nd (next week) at 3:00pm, in JA 8.13 (the SUPA room), Stephan will give a talk on

"Preparing and preserving low entropy states using ultra-cold atoms in optical lattices"

Everyone who is interested is warmly invited to attend. I’ve attached an abstract for the talk below

Very best regards,
Andrew


Abstract:
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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. A key challenge to explore many interesting quantum phases is to reach 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. Incoherent scattering of light from the lasers that form the lattices can contribute significantly to the heating. We study the robustness of many-body states to this mechanism, deriving a many-body master equation for two-component fermions and investigating how the heating is influenced by choices in the atomic physics and how it depends on the parameters in the many-body Hamiltonian.

On the other hand we consider dynamical schemes to obtain low entropy ground states of strongly interacting many body systems. The focus of our work is on ultra-cold Bose and Fermi gases in bilayer optical lattice systems with separately tunable interlayer coupling, energy offset between the layers and repulsive interactions. The case of two coupled one-dimensional chains is treated in a numerically exact manner using the adaptive time-dependent density matrix renormalization group which allows us to study the change of offset and interlayer coupling in real time. We identify parameter regimes where the ground state of the coupled system in the limit of small interlayer coupling consists of a Mott insulator in one layer and a superfluid/metallic state in the other layer can serve as an entropy reservoir. We then investigate the time-dependent dynamics of this system, studying entropy transfer between layers and the emergence of characteristic many-body correlations as we change the layer offset energy and coupling strength.



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Professor Andrew Daley

Department of Physics
University of Strathclyde
John Anderson Building
107 Rottenrow East
Glasgow G4 0NG, UK

http://qoqms.phys.strath.ac.uk
http://cnqo.phys.strath.ac.uk
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