High-contrast plasmonic-enhanced shallow spin defects in hexagonal boron nitride for quantum sensing

TL;DR

This paper demonstrates a significant enhancement in the optical and magnetic sensing capabilities of shallow spin defects in hexagonal boron nitride through plasmonic effects, achieving record-high contrast and improved sensitivity for quantum sensing.

Contribution

It introduces a novel method combining shallow boron vacancy defects with plasmonic gold-film waveguides to greatly enhance ODMR contrast and photoluminescence in hBN.

Findings

Achieved 46% ODMR contrast at room temperature.

Enhanced photoluminescence of hBN defects by up to 17-fold.

Improved magnetic field detection sensitivity.

Abstract

The recently discovered spin defects in hexagonal boron nitride (hBN), a layered van der Waals material, have great potential in quantum sensing. However, the photoluminescence and the contrast of the optically detected magnetic resonance (ODMR) of hBN spin defects are relatively low so far, which limits their sensitivity. Here we report a record-high ODMR contrast of 46$\%$ at room temperature, and simultaneous enhancement of the photoluminescence of hBN spin defects by up to 17-fold by the surface plasmon of a gold-film microwave waveguide. Our results are obtained with shallow boron vacancy spin defects in hBN nanosheets created by low-energy He$^+$ ion implantation, and a gold-film microwave waveguide fabricated by photolithography. We also explore the effects of microwave and laser powers on the ODMR, and improve the sensitivity of hBN spin defects for magnetic field detection. Our results support the promising potential of hBN spin defects for nanoscale quantum sensing.