Bose-Hubbard Models in Confining Potentials: An Inhomogeneous Mean-Field Theory

We present an extensive study of Mott insulator (MI) and superfluid (SF) shells in Bose-Hubbard (BH) models for bosons in optical lattices with harmonic traps. For this we develop an inhomogeneous mean-field theory. Our results for the BH model with one type of spinless bosons agrees quantitatively...

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Bibliographic Details
Published in:arXiv.org 2012-01
Main Authors: Pai, Ramesh V, Jamshid Moradi Kurdestany, Sheshadri, K, Pandit, Rahul
Format: Article
Language:English
Subjects:
Bosons
Computer simulation
Confining
Fluids
Mathematical models
Mean field theory
Optical lattices
Phase diagrams
Superfluidity
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Summary:We present an extensive study of Mott insulator (MI) and superfluid (SF) shells in Bose-Hubbard (BH) models for bosons in optical lattices with harmonic traps. For this we develop an inhomogeneous mean-field theory. Our results for the BH model with one type of spinless bosons agrees quantitatively with quantum Monte Carlo (QMC) simulations. Our approach is numerically less intensive than such simulations, so we are able to perform calculation on experimentally realistic, large 3D systems, explore a wide range of parameter values, and make direct contact with a variety of experimental measurements. We also generalize our inhomogeneous mean-field theory to study BH models with harmonic traps and (a) two species of bosons or (b) spin-1 bosons. With two species of bosons we obtain rich phase diagrams with a variety of SF and MI phases and associated shells, when we include a quadratic confining potential. For the spin-1 BH model we show, in a representative case, that the system can display alternating shells of polar SF and MI phases; and we make interesting predictions for experiments in such systems.
ISSN:2331-8422
DOI:10.48550/arxiv.1201.1642