Collective excitations in anF= 2 Bose-Einstein condensate

Abstract

We calculate the collective excitations in a homogeneous F = 2 spinor condensate in the absence of the magnetic field and also in a strong magnetic field. Almost all the excitations for a zero magnetic field are found to have either the Bogoliubov form or the free-particle form. We relate our results for a strong magnetic field to the concept of fragmented condensates and note that some observable quantities such as the speed of sound for the cyclic state depend on the existence of a relative phase between the spinor amplitudes for the M = ±2,0 atoms.