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TT: Fachverband Tiefe Temperaturen

TT 9: CE: (General) Theory 1

TT 9.4: Talk

Monday, March 14, 2011, 14:45–15:00, HSZ 201

Effective models for gapped phases of strongly correlated quantum lattice models — Hong Yu Yang and •Kai Phillip Schmidt — Lehrstuhl für Theoretische Physik I, TU Dortmund, 44221 Dortmund, Germany

We present a robust scheme to derive effective models non-perturbatively for quantum lattice models when at least one degree of freedom is gapped. A combination of graph theory and the method of continuous unitary transformations (gCUTs) is shown to efficiently capture all zero-temperature fluctuations in a controlled spatial range. The gCUT can be used either for effective quasi-particle descriptions or for effective low-energy descriptions in case of infinitely degenerate subspaces. We illustrate the method for 1d and 2d lattice models yielding convincing results in the thermodynamic limit. Various extensions and perspectives of the gCUT are discussed.