Characteristic quantities for nonequilibrium Bose systems

TL;DR

This paper explores characteristic quantities like effective temperature and Mach number to quantify nonequilibrium states in Bose systems, illustrating their application through a shaken trap Bose-Einstein condensate with eight distinct nonequilibrium states.

Contribution

It introduces a classification scheme for nonequilibrium Bose states based on characteristic quantities and demonstrates this with experimental creation and modeling of various vortex states.

Findings

Eight distinct nonequilibrium states identified in Bose-Einstein condensates.

Characteristic quantities effectively distinguish different nonequilibrium states.

Modeling with nonlinear Schrödinger equation supports the classification.

Abstract

The paper discusses what characteristic quantities could quantify nonequilibrium states of Bose systems. Among such quantities, the following are considered: effective temperature, Fresnel number, and Mach number. The suggested classification of nonequilibrium states is illustrated by studying a Bose-Einstein condensate in a shaken trap, where it is possible to distinguish eight different nonequilibrium states: weak nonequilibrium, vortex germs, vortex rings, vortex lines, deformed vortices, vortex turbulence, grain turbulence, and wave turbulence. Nonequilibrium states are created experimentally and modeled by solving the nonlinear Schr\"odinger equation.