Two-fluid hydrodynamics of cold atomic bosons under influence of the quantum fluctuations at non-zero temperatures

TL;DR

This paper develops an extended two-fluid hydrodynamic model for ultracold Bose atoms at finite temperatures, incorporating quantum fluctuations and thermal effects, derived from microscopic principles.

Contribution

It introduces a generalized pressure flux evolution equation for finite temperatures, accounting for quantum fluctuations and interactions in a two-fluid model.

Findings

Pressure evolution equation shows no short-range interaction contribution.

Pressure flux evolution includes interaction effects leading to quantum fluctuations.

Model derived directly from microscopic many-particle Schrödinger equation.

Abstract

Ultracold Bose atoms is the physical system, where the quantum and nonlinear phenomena play crucial role. Ultracold bosons are considered at the small finite temperatures. Bosons are considered as two different fluids: Bose-Einstein condensate and normal fluid (the thermal component). An extended hydrodynamic model is obtained for both fluids, where the pressure evolution equations and the pressure flux third rank tensor evolution equations are considered along with the continuity and Euler equations. It is found that the pressure evolution equation contains zero contribution of the short-range interaction. The pressure flux evolution equation contains the interaction which gives the quantum fluctuations in the zero temperature limit. Here, we obtain its generalization for the finite temperature. The contribution of interaction in the pressure flux evolution equation which goes to zero in the zero temperature limit is found. The model is obtained via the straightforward derivation from the microscopic many-particle Schrodinger equation in the coordinate representation.