The Langevin Noise Approach for Lossy Media and the Lossless Limit

TL;DR

This paper compares the Langevin noise approach with normal mode quantization for macroscopic electromagnetics, demonstrating that in lossless closed systems, both methods converge to the same cavity mode expansion, clarifying their relationship.

Contribution

It provides a detailed comparison between the Langevin noise approach and normal mode quantization, highlighting their equivalence in lossless closed systems.

Findings

Langevin noise approach reduces to cavity mode expansion in lossless systems

The applicability of the Langevin noise method is discussed and clarified

Examples demonstrate the convergence of the two quantization methods

Abstract

The Langevin noise approach for quantization of macroscopic electromagnetics for three-dimensional, inhomogeneous environments is compared with normal mode quantization. Recent works on the applicability of the method are discussed, and several examples are provided showing that for closed systems the Langevin noise approach reduces to the usual cavity mode expansion method when loss is eliminated.