English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This work continues the investigation of radiation phenomena from atom-fieldinteractions, extending our earlier study of quantum radiation from astationary atom's internal degree of freedom, modeled by a harmonic oscillator,to the emittance of classical radiation. By assuming that the atom interactswith a quantum scalar field initially in a coherent state, we show how astochastic component of the internal dynamics of the atom arises from thevacuum fluctuations of the field, resulting in the emittance of quantumradiation, whose reaction induces quantum dissipation in the internal dynamics.We also show how the deterministic mean field drives the internal classicalmean component to emit classical radiation and receive classical radiationreaction. Both components are statistically distinct and fully decoupled. It isclearly seen that the effects of the vacuum fluctuations of the field arematched with those of quantum radiation reaction, not with classical radiationreaction, as the folklore goes. In contrast to the quantum component of theatom's internal dynamics, which always equilibrates, the relaxation dynamics ofthe classical component largely depends on the late-time behavior of the meanfield. For the values of the parameters defining the coherent state of thefield much greater than unity, if the mean field remains periodic, then theinternal dynamics of the atom will appear classical and periodic. If the meanfield diminishes with time, then the classical component of the atom's internaldynamics subsides but the quantum component will abide and dynamicallyequilibrate. This also explains why quantum radiation from a stationary atom isnot observed, and a probe located far away only sees classical radiation. Ouranalysis therefore paints a continuum landscape starting from vacuumfluctuations in the quantum field to classical radiation and radiationreaction.

Quantum Radiation and Dissipation in Relation to Classical Radiation and Radiation Reaction