A Dynamical Self-Consistent Finite Temperature Kinetic Theory: The ZNG Scheme

TL;DR

This paper reviews the ZNG scheme, a self-consistent kinetic theory for modeling trapped weakly-interacting quantum gases at finite temperatures, capturing both condensate and thermal cloud dynamics.

Contribution

It provides a comprehensive overview of the ZNG method, combining dissipative Gross-Pitaevskii and quantum Boltzmann equations for finite temperature quantum gases.

Findings

Application to damping of collective modes

Analysis of vortex dynamics at finite temperature

Description of regimes from mean-field to hydrodynamic

Abstract

We review a self-consistent scheme for modelling trapped weakly-interacting quantum gases at temperatures where the condensate coexists with a significant thermal cloud. This method has been applied to atomic gases by Zaremba, Nikuni, and Griffin, and is often referred to as ZNG. It describes both mean-field-dominated and hydrodynamic regimes, except at very low temperatures or in the regime of large fluctuations. Condensate dynamics are described by a dissipative Gross-Pitaevskii equation (or the corresponding quantum hydrodynamic equation with a source term), while the non-condensate evolution is represented by a quantum Boltzmann equation, which additionally includes collisional processes which transfer atoms between these two subsystems. In the mean-field-dominated regime collisions are treated perturbatively and the full distribution function is needed to describe the thermal cloud, while in the hydrodynamic regime the system is parametrised in terms of a set of local variables. Applications to finite temperature induced damping of collective modes and vortices in the mean-field-dominated regime are presented.