Dressed infrared quantum information

TL;DR

This paper explores the infrared sector of quantum electrodynamics using dressed states, revealing how unobservable photons cause decoherence in electron measurements and discussing implications for the black hole information paradox.

Contribution

It applies the dressed-state formalism to analyze IR effects in QED, highlighting decoherence mechanisms and potential links to black hole information issues.

Findings

Infrared photons cause decoherence in electron momentum measurements.

Dressed states lead to an IR-finite S-matrix in QED.

Implications for black hole information paradox are discussed.

Abstract

We study information-theoretic aspects of the infrared sector of quantum electrodynamics, using the dressed-state approach pioneered by Chung, Kibble, Faddeev-Kulish and others. In this formalism QED has an IR-finite S-matrix describing the scattering of electrons dressed by coherent states of photons. We show that measurements sensitive only to the outgoing electronic degrees of freedom will experience decoherence in the electron momentum basis due to unobservable photons in the dressing. We make some comments on possible refinements of the dressed-state formalism, and how these considerations relate to the black hole information paradox.