arXiv:cond-mat/0509256 · Physical Review A

Collective modes and the broken symmetry of a rotating attractive Bose gas in an anharmonic trap

Anssi Collin

Published Jan 12, 2006• 18 citations

Abstract

We study the rotational properties of an attractively interacting Bose gas in an anharmonic potential. Low-energy excitations for the two possible rotational ground-state configurations (vortex and the center-of-mass rotating state) are analyzed. The vortex excitation spectrum is all positive for weak couplings, but as the interactions become stronger, the energy of the lowest mode decreases rapidly to a negative value. The broken rotational symmetry involved in the center-of-mass rotating state induces the appearance of an extra zero-energy mode in the Bogoliubov spectrum. The excitations of the center-of-mass rotational state also demonstrate the coupling between the center of mass and relative motions.

DOI: 10.1103/physreva.73.013611

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