Two dispersion curves for a one-dimensional interacting Bose gas under zero boundary conditions

Abstract

The influence of boundaries and non-point character of interatomic interaction on the dispersion law has been studied for a uniform Bose gas in a one-dimensional vessel. The non-point character of interaction was taken into account using the Gross equation, which is more general than the Gross-Pitaevskii one. In the framework of this approach, the well-known Bogolyubov dispersion mode \hbar\omega(k)=[(\hbar^{2}k^{2}/2m) ^{2}+qn\nu(k)\hbar^{2}k^{2}/m]^{1/2} (q=1) was obtained, as well as a new one, which is described by the same formula, but with q= 1/2. The new mode emerges owing to the account of boundaries and the non-point character of interaction: this mode is absent when either the Gross equation for a cyclic system or the Gross-Pitaevskii equation for a cyclic system or a system with boundaries is solved. Capabilities for the new mode to be observed are discussed.