Coupling Spin Defects in a Layered Material to Nanoscale Plasmonic Cavities

TL;DR

This paper demonstrates a scalable method to significantly enhance the photoluminescence of spin defects in hexagonal boron nitride by coupling them to a plasmonic cavity, improving quantum sensing capabilities.

Contribution

The study introduces a novel plasmonic cavity design that boosts emission from spin defects in 2D materials, advancing quantum sensing applications.

Findings

Two orders of magnitude increase in photoluminescence.

Twofold enhancement in magnetic resonance contrast.

Potential for improved quantum sensing devices.

Abstract

Spin defects in hexagonal boron nitride, and specifically the negatively charged boron vacancy (VB) centres, are emerging candidates for quantum sensing. However, the VB defects suffer from low quantum efficiency and as a result exhibit weak photoluminescence. In this work, we demonstrate a scalable approach to dramatically enhance the VB- emission by coupling to a plasmonic gap cavity. The plasmonic cavity is composed of a flat gold surface and a silver cube, with few-layer hBN flakes positioned in between. Employing these plasmonic cavities, we extracted two orders of magnitude in photoluminescence enhancement associated with a corresponding 2 fold enhancement in optically detected magnetic resonance contrast. The work will be pivotal to progress in quantum sensing employing 2D materials, and realisation of nanophotonic devices with spin defects in hexagonal boron nitride.