Mott-insulator-to-superfluid transition in the Bose-Hubbard model: A strong-coupling approach

Journal Article · Tue Mar 01 04:00:00 EST 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.71.033629· OSTI ID:20650480

Sengupta, K; Dupuis, N ^[1]

---

1. 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, Journal Name: Physical Review. A Journal Issue: 3 Vol. 71; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR 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