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SUMMARY:Ultracold atoms and fermionic simulations - Prof. Matthias Troyer\
 , ETH Zürich
DTSTART:20110428T131500Z
DTEND:20110428T141500Z
UID:TALK28206@talks.cam.ac.uk
CONTACT:Dr G Moller
DESCRIPTION:The accurate simulation of fermionic quantum many body problem
 s is one of the most important challenges in theoretical physics\, with hu
 ge impact especially on the understanding and design of materials. However
 \, the exponential scaling of the Hilbert space make direct simulations im
 possible for all but the smallest systems and Monte Carlo simulations suff
 er from the negative sign problem. The goal thus has to be to develop effi
 cient approximate methods for fermionic systems. I will report on recent p
 rogress in the simulation of fermionic systems\, especially in the context
  of ultracold atomic gases in optical lattices. In deep optical lattice fe
 rmionic gases are well described by the Hubbard model\, which we can now a
 ccurately simulate down to the Néel temperature\, substantially lower tha
 n the lowest temperature achieved in experiments so far. In shallow optica
 l lattices the simulation and the physics become more complex\, as band mi
 xing and orbital effects become important\, and multi-band models are hard
  to derive and simulate. Here we propose to use density functional theory 
 for such systems\, using a new exchange correlation functional for ultraco
 ld atomic gases instead of electrons. This lets us use all the tools devel
 oped for materials simulations also for the simulation of atomic gases. In
  the future\, comparison to controlled experiments will  allow to test and
  improve density functionals for strongly correlated fermionic systems\, a
 nd thus in return also improve simulation methods for materials.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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