On the response of detectors in classical electromagnetic backgrounds

TL;DR

This paper investigates how a non-linearly coupled detector responds to a quantized scalar field in classical electromagnetic backgrounds, revealing that the detector's response correlates with particle production but not directly with particle number.

Contribution

It demonstrates that in inertial motion, the detector responds only to particle-producing electromagnetic backgrounds, highlighting a non-proportional relationship between response and particle count.

Findings

Detector responds only to particle-producing backgrounds

Response is not proportional to the number of particles

Inertial detectors detect particles only from backgrounds that produce particles

Abstract

I study the response of a detector that is coupled non-linearly to a quantized complex scalar field in different types of classical electromagnetic backgrounds. Assuming that the quantum field is in the vacuum state, I show that, when in {\it inertial} motion, the detector responds {\it only} when the electromagnetic background produces particles. However, I find that the response of the detector is {\it not} proportional to the number of particles produced by the background.