The European Physical Journal B

, Volume 61, Issue 3, pp 277–285 | Cite as

Ground state properties of an asymmetric Hubbard model for unbalanced ultracold fermionic quantum gases

Solids and Liquids

Abstract.

In order to describe unbalanced ultracold fermionic quantum gases on optical lattices in a harmonic trap, we investigate an attractive (U < 0) asymmetric (t≠t) Hubbard model with a Zeeman-like magnetic field. In view of the model's spatial inhomogeneity, we focus in this paper on the solution at Hartree-Fock level. The Hartree-Fock Hamiltonian is diagonalized with particular emphasis on superfluid phases. For the special case of spin-independent hopping we analytically determine the number of solutions of the resulting self-consistency equations and the nature of the possible ground states at weak coupling. We present the phase diagram of the homogeneous system and numerical results for unbalanced Fermi-mixtures obtained within the local density approximation. In particular, we find a fascinating shell structure, involving normal and superfluid phases. For the general case of spin-dependent hopping we calculate the density of states and the possible superfluid phases in the ground state. In particular, we find a new magnetized superfluid phase.

PACS.

03.75.Hh Static properties of condensates; thermodynamical, statistical, and structural properties 39.25.+k Atom manipulation (scanning probe microscopy, laser cooling, etc.) 71.10.Fd Lattice fermion models (Hubbard model, etc.) 

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Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2008

Authors and Affiliations

  1. 1.KOMET 337, Institut für Physik, Johannes Gutenberg-UniversitätMainzGermany

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