Spin-1 bosons with coupled ground states in optical lattices

K. V. Krutitsky and R. Graham
Phys. Rev. A 70, 063610 – Published 13 December 2004

Abstract

The superfluid–Mott-insulator phase transition of ultracold spin-1 bosons with ferromagnetic and antiferromagnetic interactions in an optical lattice is theoretically investigated. Two counterpropagating linearly polarized laser beams with the angle θ between the polarization vectors (linθlin configuration), driving an Fg=1 to Fe=1 internal atomic transition, create the optical lattice and at the same time couple atomic ground states with magnetic quantum numbers m=±1. Due to the coupling the system can be described as a two-component one. At θ=0 the system has a continuous isospin symmetry, which can be spontaneously broken, thereby fixing the number of particles in the atomic components. The phase diagram of the system and the spectrum of collective excitations, which are density waves and isospin waves, are worked out. In the case of ferromagnetic interactions, the superfluid–Mott-insulator phase transition is always second order, but in the case of antiferromagnetic interactions for some values of system parameters it is first order and the superfluid and Mott phases can coexist. Varying the angle θ one can control the populations of atomic components and continuously turn on and tune their asymmetry.

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  • Received 24 July 2004

DOI:https://doi.org/10.1103/PhysRevA.70.063610

©2004 American Physical Society

Authors & Affiliations

K. V. Krutitsky and R. Graham

  • Fachbereich Physik der Universität Duisburg-Essen, Campus Essen, Universitätsstr. 5, D-45117 Essen, Germany

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Issue

Vol. 70, Iss. 6 — December 2004

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