Brownian motion of a charged test particle driven by vacuum fluctuations near a dielectric half-space

TL;DR

This paper investigates how vacuum electromagnetic fluctuations near a dielectric boundary influence the Brownian motion of a charged particle, revealing that realistic dielectric properties prevent negative velocity dispersions seen in idealized models.

Contribution

It provides the first detailed analysis of vacuum fluctuation effects on charged particles near realistic dielectric interfaces, contrasting with idealized perfect conductor models.

Findings

Velocity dispersions are affected by dielectric susceptibility.

Negative velocity dispersions are absent in realistic dielectric cases.

Velocity dispersions in parallel directions do not decay over time.

Abstract

We study the Brownian motion of a charged test particle driven by quantum electromagnetic fluctuations in the vacuum region near a non-dispersive and non-absorbing dielectric half-space and calculate the mean squared fluctuations in the velocity of the test particle. Our results show that a nonzero susceptibility of the dielectrics has its imprints on the velocity dispersions of the test particles. The most noteworthy feature in sharp contrast to the case of an idealized perfectly conducting interface is that the velocity dispersions in the parallel directions are no longer negative and does not die off in time, suggesting that the potentially problematic negativeness of the dispersions in those directions in the case of perfect conductors is just a result of our idealization and does not occur for real material boundaries.