English

Can a localised quantum system see soft photons?

High Energy Physics - Theory 2021-08-11 v1 General Relativity and Quantum Cosmology Quantum Physics

Abstract

We ask whether soft photons, defined by asymptotic charges, can have consequences for the outcome of localised quantum processes. We consider a spatially localised two-state system, at rest in flat spacetime, coupled to a U(1)U(1) gauge invariant charged scalar field. We find that the system's de-excitation rate does depend on the soft charges that correspond to the radial component of the electric field dressing at the asymptotic infinity; the excitation rate, by contrast, remains zero, regardless of the soft charges. Some implications are discussed.

Keywords

Cite

@article{arxiv.2108.04278,
  title  = {Can a localised quantum system see soft photons?},
  author = {Sanved Kolekar and Jorma Louko},
  journal= {arXiv preprint arXiv:2108.04278},
  year   = {2021}
}

Comments

27 pages

R2 v1 2026-06-24T04:57:55.439Z