Quantum gray solitons in confining potentials

TL;DR

This paper investigates hole-like excitations called Lieb II modes in a confined Bose liquid, showing how gray solitons and phonon radiation influence their properties and experimental observability.

Contribution

It introduces a semiclassical approach to analyze Lieb II modes in a confined Bose gas and explores their lifetime and experimental resolution.

Findings

Gray solitons can be quantized to describe Lieb II modes.

Phonon radiation causes finite lifetime of the modes.

Most Lieb II levels are experimentally resolvable in large atom traps.

Abstract

We define and study hole-like excitations (the Lieb II mode) in a weakly interacting Bose liquid subject to external confinement. These excitations are obtained by semiclassical quantization of gray solitons propagating on top of a Thomas-Fermi background. Radiation of phonons by an accelerated gray soliton leads to a finite life-time for the trapped Lieb II mode. It is shown that, for a large number of trapped atoms, most of the Lieb II levels can be experimentally resolved.