Pronounced non-Markovian features in multiply-excited, multiple-emitter waveguide-QED: Retardation-induced anomalous population trappin

TL;DR

This paper demonstrates that non-Markovian effects, specifically retardation, can qualitatively alter the dynamics of a multi-emitter waveguide-QED system, leading to phenomena like anomalous population trapping that Markovian models cannot reproduce.

Contribution

It provides the first example showing how retardation induces non-Markovian effects that fundamentally change quantum optical system behavior, including population trapping and novel steady states.

Findings

Retardation causes anomalous population trapping.

Markovian approximation fails to capture key dynamics.

A new steady state with partial excitation persists.

Abstract

The Markovian approximation is widely applied in the field of quantum optics due to the weak frequency dependence of the vacuum field amplitude, and in consequence non-Markovian effects are typically regarded to play a minor role in the optical electron-photon interaction. Here, we give an example where non-Markovianity changes the qualitative behavior of a quantum optical system, rendering the Markovian approximation quantitatively and qualitatively insufficient. Namely, we study a multiple-emitter, multiple-excitation waveguide quantum-electrodynamic (waveguide-QED) system and include propagation time delay. In particular, we demonstrate anomalous population trapping as a result of the retardation in the excitation exchange between the waveguide and three initially excited emitters. Allowing for local phases in the emitter-waveguide coupling, this population trapping cannot be recovered using a Markovian treatment, proving the essential role of non-Markovian dynamics in the process. Furthermore, this time-delayed excitation exchange allows for a novel steady state, in which one emitter decays entirely to its ground state while the other two remain partially excited.