Short-Wave Excitations in Non-Local Gross-Pitaevskii Model

TL;DR

This paper demonstrates that a non-local Gross-Pitaevskii model can describe both long- and short-wave excitations in Bose-condensates, revealing a roton minimum similar to superfluid helium, influenced by inter-particle interactions.

Contribution

It introduces a non-local Gross-Pitaevskii equation framework capable of capturing short-wave excitations and roton features in Bose-condensate systems.

Findings

Spectrum mimics Landau spectrum with roton minimum

Roton minimum wavelength is close to interaction range

Attractive interactions reduce the roton spectrum domain

Abstract

It is shown, that a non-local form of the Gross-Pitaevskii equation allows to describe not only the long-wave excitations, but also the short-wave ones in the systems with Bose-condensate. At given parameter values, the excitation spectrum mimics the Landau spectrum of quasi-particle excitations in superfluid Helium with roton minimum. The excitation wavelength, at which the roton minimum exists, is close to the inter-particle interaction range. It is shown, that the existence domain of the spectrum with a roton minimum is reduced, if one accounts for an inter-particle attraction.