Quantum Electrodynamics of Dicke States: Resonant One-Photon Exchange and Entangled Decay Rate

TL;DR

This paper develops a covariant perturbation theory approach to calculate the interatomic potential and decay rate modifications for entangled Dicke states, incorporating retardation effects and virtual photon exchange.

Contribution

It introduces a full relativistic framework for analyzing one-photon exchange interactions and decay rate corrections in entangled atomic states, including retardation and gauge considerations.

Findings

Derived formulas for distance-dependent decay rate modifications.

Quantified enhancement and suppression of superradiant and subradiant states.

Applied the theory to hydrogen atom examples with specific excited states.

Abstract

We calculate the one-photon exchange contribution to the interatomic interaction potential between electrically neutral, identical atoms, one of which is assumed to be in an excited state, by matching the scattering matrix (S matrix) element with the effective Hamiltonian. This approach allows us to use covariant perturbation theory, where the two possible time orderings of emission and absorption are summarized in a single Feynman amplitude. Our results encompass the full retardation correction to the one-photon exchange van-der-Waals potential. We employ the temporal gauge for the virtual photon propagator. Based on the Feynman prescription, we obtain the imaginary part of the interaction energy, which leads to an interaction-induced correction to the decay rate. Our results lead to precise formulas for the distance-dependent enhancement and suppression of the decay rates of entangled superradiant and subradiant Dicke state, as a function of the interatomic distance. We apply the result to an example calculation involving two hydrogen atoms, one of which is in the ground state, the other in an excited P state.