Collective modes of trapped spinor Bose condensates

TL;DR

This paper analytically investigates the collective excitations of spinor Bose-Einstein condensates in a trapped optical lattice, revealing how lattice parameters influence phonon frequencies and phase transitions.

Contribution

It provides the first analytical expressions for confined polar and ferromagnetic Goldstone modes in spinor BECs within a harmonic trap and optical lattice.

Findings

Optical lattice intensity shifts phonon frequencies.

High lattice intensities make excitation spectra independent of self-interactions.

Features of Goldstone modes evolve across ferromagnetic and polar phases.

Abstract

We study the richer structures of quasi-one-dimensional Bogoliubov-de Genes collective excitations of F = 1 spinor Bose-Einstein condensate in a harmonic trap potential loaded in an optical lattice. Employing a perturbative method we report general analytical expressions for the confined collective polar and ferromagnetic Goldstone modes. In both cases the excited eigenfrequencies are given as function of the 1D effective coupling constants, trap frequency and optical lattice parameters. It is shown that the main contribution of the optical lattice laser intensity is to shift the confined phonon frequencies. Moreover, for high intensities, the excitation spectrum becomes independent of the self-interaction parameters. We reveal some features of the evolution for the Goldstone modes as well as the condensate densities from the ferromagnetic to the polar phases.