Roton Spectrum of Condensed Bose Systems

Abstract

The study of the behaviors of the roton excitation in a Bose system is performed on the basis of Bogoliubov’s procedure. The method of the present theory is a generalization of Bohm-Pines’ theory of electron gases to a quantum field theory. Rotons in our model are connected with the quasi-particles described by the translational motion in the condensate wavefunction, thus they are viewed just like as solitons in a nonlinear field theory. We will show that the roton-momentum P₀ is intimately linked to the vortical motion in the system. The rest energy of roton is also obtained.