Correlated bosons on a lattice: Dynamical mean-field theory for Bose-Einstein condensed and normal phases - Condensed Matter > Other Condensed MatterReportar como inadecuado




Correlated bosons on a lattice: Dynamical mean-field theory for Bose-Einstein condensed and normal phases - Condensed Matter > Other Condensed Matter - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We formulate a bosonic dynamical mean-field theory B-DMFT which provides acomprehensive, thermodynamically consistent framework for the theoreticalinvestigation of correlated lattice bosons. The B-DMFT is applicable forarbitrary values of the coupling parameters and temperature and becomes exactin the limit of high spatial dimensions d or coordination number Z of thelattice. In contrast to its fermionic counterpart the construction of theB-DMFT requires different scalings of the hopping amplitudes with Z dependingon whether the bosons are in their normal state or in the Bose-Einsteincondensate. A detailed discussion of how this conceptual problem can beovercome by performing the scaling in the action rather than in the Hamiltonianitself is presented. The B-DMFT treats normal and condensed bosons on equalfooting and thus includes the effects caused by their dynamic coupling. Itreproduces all previously investigated limits in parameter space such as theBeliaev-Popov and Hartree-Fock-Bogoliubov approximations and generalizes theexisting mean-field theories of interacting bosons. The self-consistencyequations of the B-DMFT are those of a bosonic single-impurity coupled to tworeservoirs corresponding to bosons in the condensate and in the normal state,respectively. We employ the B-DMFT to solve a model of itinerant and localized,interacting bosons analytically. The local correlations are found to enhancethe condensate density and the Bose-Einstein condensate BEC transitiontemperature T {BEC}. This effect may be used experimentally to increase T {BEC}of bosonic atoms in optical lattices.



Autor: Krzysztof Byczuk, Dieter Vollhardt

Fuente: https://arxiv.org/







Documentos relacionados