Programmable Quantum Mode Switches via Plasmonic Toroidal Nanoantennae

TL;DR

This paper demonstrates how toroidal nanoantennae can be used to switch and control quantum emission spectra, enabling advanced applications in biosensing and quantum information processing.

Contribution

It introduces a novel approach using plasmonic toroidal nanoantennae for high-contrast spectral switching of quantum emitters based on Fano interference.

Findings

Achieved full spectral switching near 850 nm by suppressing decay channels.

Demonstrated enhanced transparency bandwidth with multiple quantum objects.

Showed individual spectral responses can be controlled via detuning.

Abstract

The ability to switch and program the spectral response of quantum modes via deterministically located plasmonic nanoantennae presents opportunities for wide spectrum of applications from biosensors to quantum computing. Due to its topology, toroidal nanoantenna (TNA) focuses immense amount of three-dimensional (3D) local electric field by toroidal moment while allowing pre and post positioning around quantum emitters (QEs). Here, within local-response finite difference time domain (FDTD) simulations, we demonstrate high-contrast spectral switching of the radiative decay channel of a dipolar QE coupled to a TNA by introducing effective Lorentzian quantum objects (QOs). At optimized TNA geometries, Fano interference between the broadband plasmonic continuum and narrow quantum transitions of QOs suppresses both radiative and non-radiative decay channels near 850 nm, yielding an observable full switching that traps energy within the hybrid mode instead of re-emitting it. To show the promises of the concept, we further demonstrate systems with multiple QOs where spectral degeneracy enhances the transparency bandwidth, while detuning generates distinct minima, enabling individually addressable spectral responses. These results establish plasmonic TNAs as promising architectures for spectral detection and individual mode switching of single- or multi-QO configurations and empowers the user for the implementation of photonic processing of continuous photon sources.