Fluctuation and interaction induced instability of dark solitons in single and binary condensates

TL;DR

This paper investigates how solitons in single and binary condensates lead to instabilities and topological changes, revealing the role of quantum depletion and Goldstone modes in these phenomena.

Contribution

It demonstrates that solitons induce dynamical instability via quantum depletion and identifies Goldstone modes in two-species condensates at phase separation.

Findings

Solitons enhance quantum depletion, causing instability.

Two Goldstone modes emerge at phase separation.

Solitons alter the density profile topology.

Abstract

We show that the presence of soliton in a single-species condensate, at zero temperature, enhances the quantum depletion sufficient enough to induce dynamical instability of the system. We also predict that for two-species condensates, two Goldstone modes emerge in the excitation spectrum at phase separation. Of these, one is due to the presence of the soliton. We use Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode evolution, and demonstrate that when the anomalous mode collides with a higher energy mode it renders the solitonic state oscillatory unstable. We also report soliton induced change in the topology of the density profiles of the two-species condensates at phase-separation.