Excitation spectrum of a toroidal spin-1 Bose-Einstein condensate

TL;DR

This paper analytically calculates the excitation spectrum of a toroidal spin-1 Bose-Einstein condensate, revealing conditions for rotonlike spectra and instabilities influenced by magnetic fields and trapping parameters.

Contribution

It provides an analytical framework for understanding the excitation spectrum and instabilities in a toroidal spin-1 BEC with vortices, validated by numerical simulations.

Findings

Rotonlike excitation spectrum can be achieved.

Stable condensates can become unstable by tuning magnetic field or trap.

Particle density measurements reveal instability structures.

Abstract

We calculate analytically the Bogoliubov excitation spectrum of a toroidal spin-1 Bose-Einstein condensate that is subjected to a homogeneous magnetic field and contains vortices with arbitrary winding numbers in the $m_F=\pm 1$ components of the hyperfine spin. We show that a rotonlike spectrum can be obtained, or an initially stable condensate can be made unstable by adjusting the magnitude of the magnetic field or the trapping frequencies. The structure of the instabilities can be analyzed by measuring the particle densities of the spin components. We confirm the validity of the analytical calculations by numerical simulations.