Acceleration-induced radiation from a qudit particle detector model

TL;DR

This paper nonperturbatively analyzes acceleration-induced radiation from a gapless qudit Unruh-DeWitt detector, revealing the emission rate's dependence on initial states and distinguishing it from classical sources.

Contribution

It demonstrates that the emission rate depends on the detector's initial state and shows that gapless detectors cannot be approximated as structureless classical sources.

Findings

Certain initial states do not produce radiation.

The radiation forms a multimode coherent state.

The emission rate relates to Larmor's formula with state-dependent factors.

Abstract

We nonperturbatively examine the emission rate of acceleration-induced radiation from a uniformly accelerated gapless qudit-type Unruh-DeWitt detector. We find that the emission rate can be written as Larmor's formula multiplied by a factor that depends on the detector's initial state. In particular, certain initial states of integer-spin detectors do not produce radiation. Although the appearance of Larmor's formula may suggest a classical phenomenon, we argue that the resulting radiation is fundamentally distinct from that of structureless classical sources, as it evolves into a multimode coherent state correlated with the detector's internal degree of freedom. Thus, gapless detectors cannot be treated as structureless sources, as previously proposed.