Strongly entangled system-reservoir dynamics with multiphoton pulses beyond the two-excitation limit: Exciting the atom-photon bound state

TL;DR

This paper investigates the complex dynamics of a two-level quantum system interacting with a waveguide, showing that multi-photon pulses can enhance steady-state excitation beyond traditional limits.

Contribution

It introduces a matrix product state approach to analyze non-Markovian feedback and demonstrates the advantage of multi-photon pulses in trapping excitation.

Findings

Multi-photon pulses can achieve higher steady-state excitation than initial excitation.

Stimulated emission enhances trapping probability for large feedback delays.

Multi-photon excitation surpasses two-excitation limit in atom-photon bound states.

Abstract

Within the matrix product state framework, we study the non-Markovian feedback dynamics of a two-level system interacting with the electromagnetic field inside a semi-infinite waveguide where the excitation of an atom-photon bound state is possible. Taking the steady-state excitation of the emitter as a figure of merit, we compare the trapped excitation for an initially excited quantum emitter and an emitter prepared via quantized pulses containing up to four photons. In the latter case, we find that for large feedback delay times, multi-photon pulses can yield a significantly higher steady-state excitation than possible with an initially excited emitter since the stimulated emission process can enhance the trapping probability in comparison to the spontaneous decay of an initially excited emitter.