Multifrequency multi-qubit entanglement based on plasmonic hot spots

TL;DR

This paper presents a theoretical approach to generate multi-qubit entanglement at different frequencies using plasmonic hot spots, with significantly prolonged entanglement durations compared to photonic cavities.

Contribution

It introduces a rigorous electromagnetic Green's tensor method to study strong coupling and demonstrates multi-frequency entanglement in metallic nanoparticle clusters.

Findings

Multi-qubit entanglement can be achieved at different frequencies in hot spots.

Entanglement duration can be two orders longer than in photonic cavities.

Entanglement is suppressed at single scattering resonance frequency.

Abstract

The theoretical method to study strong coupling between an ensemble of quantum emitters (QEs) and surface plasmons excited by the nanoparticle cluster has been presented by using a rigorous first-principles electromagnetic Green's tensor technique. We have demonstrated that multi-qubit entanglement for two-level QEs can be produced at different frequencies simultaneously, when they locate in hot spots of metallic nanoparticle clusters. The duration of quantum beats for such an entanglement can reach two orders longer than that for the entanglement in a photonic cavity. The phenomenon originates from collective coupling resonance excitation of the cluster. At the frequency of single scattering resonance, the entanglement cannot be produced although the single QE spontaneous decay rate is very big