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Abstract: We use quantum Monte Carlo simulations to obtain zero-temperature statediagrams for strongly correlated lattice bosons in one and two dimensions underthe influence of a harmonic confining potential. Since harmonic traps generatea coexistence of superfluid and Mott insulating domains, we use localquantities such as the quantum fluctuations of the density and a localcompressibility to identify the phases present in the inhomogeneous densityprofiles. We emphasize the use of the -characteristic density- to produce astate diagram that is relevant to experimental optical lattice systems,regardless of the number of bosons or trap curvature and of the validity of thelocal-density approximation. We show that the critical value of U-t at whichMott insulating domains appear in the trap depends on the filling in thesystem, and it is in general greater than the value in the homogeneous system.Recent experimental results by Spielman et al. Phys. Rev. Lett. 100, 1204022008 are analyzed in the context of our two-dimensional state diagram, andshown to exhibit a value for the critical point in good agreement withsimulations. We also study the effects of finite, but low T


Author: Marcos Rigol, George G. Batrouni, Valery G. Rousseau, Richard T. Scalettar

Source: https://arxiv.org/







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