Hannover 2010 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 3: Quantum Gases: Bosons I

Q 3.4: Vortrag

Montag, 8. März 2010, 14:45–15:00, E 001

Process-chain approach to the Bose-Hubbard model — •Niklas Teichmann, Dennis Hinrichs, and Martin Holthaus — Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg, Germany

We carry out a perturbative analysis, of high order in the tunneling parameter, of the ground state of the homogeneous Bose-Hubbard model in the Mott insulator state[1]. This is done within a diagrammatic process-chain approach, derived from Kato’s representation of the many-body perturbation series, which can be implemented numerically in a straightforward manner. We compute ground-state energies, atom-atom correlation functions, density-density correlations, and occupation number fluctuations, for one-, two-, and three-dimensional lattices with arbitrary integer filling. In addition, the process-chain approach is employed for calculating the boundary between the Mott insulator phase and the superfluid phase with very high accuracy. We find a surprising scaling relation, that maps critical hopping parameters for different filling factors onto each other [2].

[1] N. Teichmann, D. Hinrichs, M. Holthaus and A. Eckardt, Phys. Rev. B 79, 224515 (2009).

[2] N. Teichmann and D. Hinrichs, EPJ B 71, 219 (2009).