Model for Motions of Impurities in Bose-Einstein Condensates

TL;DR

This paper introduces a quantum field theory model for impurities moving in Bose-Einstein Condensates, deriving key physical quantities and validating Landau's dissipation criterion through exact quantum mechanics.

Contribution

It presents a novel quantum field theoretical model for impurity motion in BECs, providing explicit formulae and demonstrating Landau's criterion within this framework.

Findings

Derived formulas for occupation number, dissipation, free energy, and depletion.

Validated Landau's criterion for energy dissipation in superfluids.

Analyzed impurity motion with constant velocity and acceleration.

Abstract

A model for classical impurities moving in Bose-Einstein Condensate (BEC) is proposed in the framework of quantum field theory and is solved within the Bogoliubov approximation at zero temperature. Several formulae are obtained for physical quantities such as the occupation number, the dissipation, the free energy, and the depletion. To illustrate this model two examples are studied; an impurity moving with i) a constant velocity and ii) a constant acceleration. Landau's criterion for energy dissipation accompanying the motion of impurities due to creation of quasi-particles in a superfluid, which was proposed on the basis of purely phenomenological argument, is obtained in the frame work of an exact quantum mechanical model.