Quantum Rotor Approach to the Mott-Insulator Transition in the Bose-Hubbard Model |
| T.P. Polak
Faculty of Physics, Adam Mickiewicz University of Poznań, Umultowska 85, 61-614 Poznań, Poland and T.K. Kopeć Institute for Low Temperatures and Structure Research, Polish Academy of Sciences, P.O.B. 1410, 50-950 Wrocław 2, Poland |
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| Received: 6 11 2007; |
| We present the novel approach to the Bose-Hubbard model using the U(1) quantum rotor description. We formulate a problem in the phase only action using an effective action formalism and obtain analytical formulae for the critical lines. We show that the nontrivial U(1) phase field configurations have an impact on the phase diagrams. The topological character of the quantum field is governed by terms of the integer charges - winding numbers n. The comparison of the presented results with recently obtained quantum Monte Carlo numerical calculations suggests that the competition between quantum effects in strongly interacting boson systems is correctly captured by our model. |
| DOI: 10.12693/APhysPolA.114.29 PACS numbers: 05.30.Jp, 03.75.Lm, 03.75.Nt |