Ramifications of topology and thermal fluctuations in quasi-2D condensates

TL;DR

This paper investigates how topology and thermal fluctuations influence the structure and quasiparticle excitations of quasi-2D Bose-Einstein condensates, revealing differences in density profiles and fluctuation behavior during topological transitions.

Contribution

It provides a detailed analysis of topological transformations and quasiparticle evolution in quasi-2D condensates using Hartree-Fock-Bogoliubov theory with the Popov approximation.

Findings

Density profile changes during topology transition

Thermal fluctuations remain multiply connected

Quasiparticle structure evolves with geometry

Abstract

We explore the topological transformation of quasi-2D Bose-Einstein condensates of dilute atomic gases, and changes in the low-energy quasiparticles associated with the geometry of the confining potential. In particular, we show the density profile of the condensate and quantum fluctuation follow the transition from a multiply to a simply connected geometry of the confining potential. The thermal fluctuations, in contrast, remain multiply connected. The genesis of the key difference lies in the structure of the low-energy quasiparticles. For which we use the Hartree-Fock-Bogoliubov, and study the evolution of quasiparticles, the dipole or the Kohn mode in particular. We, then employ the Hartree-Fock-Bogoliubov theory with the Popov approximation to investigate the density and the momentum distribution of the thermal atoms.