A. Minguzzi et al., Collective excitation frequencies of bosons in a parabolic potential with interparticle harmonic interactions, PHYS LETT A, 267(5-6), 2000, pp. 416-419
The fact that the ground-state first-order density matrix for bosons in a p
arabolic potential with interparticle harmonic interactions is known in exa
ct form is here exploited to study collective excitations in the weak-coupl
ing regime. Oscillations about the ground-state density are treated analyti
cally by a linearized equation of motion which includes a kinetic energy co
ntribution. We show that the dipole mode has the frequency of the bare trap
, in accord with the Kohn theorem, and derive explicit expressions for the
frequencies of the higher-multipole modes in terms of a frequency renormali
zed by the interactions. (C) 2000 Elsevier Science B.V. All rights reserved
.