Dipoles in blackbody radiation: Momentum fluctuations, decoherence, and drag force

TL;DR

This paper derives a comprehensive expression for the momentum diffusion constant of a small polarizable particle in blackbody radiation, linking it to decoherence, photon emission, and relativistic drag forces.

Contribution

It introduces a unified framework connecting momentum diffusion, decoherence, and drag force for particles in blackbody radiation, including relativistic effects.

Findings

Derived a general momentum diffusion constant expression.

Linked diffusion to decoherence rates in thermal environments.

Formulated the relativistic Einstein-Hopf drag force.

Abstract

A general expression is derived for the momentum diffusion constant of a small polarizable particle in blackbody radiation, and is shown to be closely related to the long-wavelength collisional decoherence rate for such a particle in a thermal environment. We show how this diffusion constant appears in the steady-state photon emission rate of two dipoles induced by blackbody radiation. We consider in addition the Einstein--Hopf drag force on a small polarizable particle moving in a blackbody field, and derive its fully relativistic form from the Lorentz transformation of forces.