Mott-insulator-to-superfluid transition in the Bose-Hubbard model: A strong-coupling approach
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, M5T 2Y4 ON (Canada)
We present a strong-coupling expansion of the Bose-Hubbard model which describes both the superfluid and the Mott phases of ultracold bosonic atoms in an optical lattice. By performing two successive Hubbard-Stratonovich transformations of the intersite hopping term, we derive an effective action which provides a suitable starting point to study the strong-coupling limit of the Bose-Hubbard model. This action can be analyzed by taking into account Gaussian fluctuations about the mean-field approximation as in the Bogoliubov theory of the weakly interacting Bose gas. In the Mott phase, we reproduce results of previous mean-field theories and also calculate the momentum distribution function. In the superfluid phase, we find a gapless spectrum and compare our results with the Bogoliubov theory.
- OSTI ID:
- 20650480
- Journal Information:
- Physical Review. A, Vol. 71, Issue 3; Other Information: DOI: 10.1103/PhysRevA.71.033629; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACTION INTEGRAL
ATOMS
BOSE-EINSTEIN GAS
BOSONS
COMPARATIVE EVALUATIONS
DISTRIBUTION FUNCTIONS
EXPANSION
FLUCTUATIONS
GAUSSIAN PROCESSES
HUBBARD MODEL
MEAN-FIELD THEORY
METALS
QUANTUM MECHANICS
SUPERFLUIDITY
TRANSFORMATIONS