We calculate the condensate fraction and the condensate and noncondensate spatial and momentum distribution of the Bose-Hubbard model in a trap. From our results, it is evident that using approximate distributions can lead to erroneous experimental estimates of the condensate. Strong interactions cause the condensate to develop pedestal-like structures around the central peak that can be mistak...

We report a multiple-site mean-field analysis of the zero-temperature phase diagram for ultracold bosons in realistic optical superlattices. The system of interacting bosons is described by a Bose-Hubbard model whose sitedependent parameters reflect the nontrivial periodicity of the optical superlattice. An analytic approach is formulated based on the analysis of the stability of a fixed-point ...

In this paper, for the first time we have studied theoretically the effect of exchange-correlation holes around electrons in GaAlAs/GaAs/GaAlAs nanostructure on the temperature-dependent dynamic dielectric function of two-dimensional electron gas by employing random phase, STLS and Hubbard approximations. Also, we have investigated another interesting system which is coupled quantum wells struc...

Anticommutator Green's functions and energy spectra of fullerene C 80 , endohedral fullerenes Lu 3 N@C Y with the Ih symmetry groups have been obtained in an analytical form within Hubbard model static fluctuation approximation. The states classified using methods group theory, allowed transitions molecules determined. On basis these spectra, interpretation experimentally observed optical absor...

After a brief discussion of the Bogoliubov inequality and possible generalizations thereof, we present a complete review of results concerning the Mermin-Wagner theorem for various many-body systems, geometries and order parameters. We extend the method to cover magnetic phase transitions in the Periodic Anderson Model as well as certain superconducting pairing mechanisms for Hubbard films. The...

Abstract We investigate the excitation spectrum and momentum distribution of ionic Bose–Hubbard model by standard basis operator method. derive Green’s functions in random phase approximation Mott insulator, superfluid, charge density wave, supersolid phases. The has gapped modes gapless Goldstone superfluid show that a peak at zone corner wave close to boundary. In addition, we demonstrate can...

Motivated by recent experiments on Mott insulators, in both iridates and ultracold atoms, we theoretically study the effects of magnetic order Mott-Hubbard excitons. In particular, focus spin-mediated doublon-holon pairing Hubbard materials. We use several complementary theoretical techniques: Mean-field theory to describe spin degrees freedom, self-consistent Born approximation characterize in...

We present fully self-consistent calculations in the fluctuation exchange approximation for the half-filled Hubbard model in 2D. A non-fermi liquid state evolves with decreasing temperature in this self-consistent model of coupled spin fluctuations and quasiparticles. The mean field phase transition to long-range antiferromagnetic order is suppressed and we find no evidence of a phase transitio...