Coupling Spin Defects in a Layered Material to Nanoscale Plasmonic Cavities

Noah Mendelson, Ritika Ritika, Mehran Kianinia, John Scott, Sejeong Kim, Johannes E. Fröch, Camilla Gazzana, Mika Westerhausen, Licheng Xiao, Seyed Sepehr Mohajerani, Stefan Strauf, Milos Toth, Igor Aharonovich, Zai-Quan Xu

Published 2021-08-05Version 1

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.