Nanoengineered Diamond Waveguide as a Robust Bright
Platform for Nanomagnetometry Using Shallow Nitrogen Vacancy Centers
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Abstract
Photonic structures in diamond are
key to most of its application in quantum technology. Here, we demonstrate
tapered nanowaveguides structured directly onto the diamond substrate
hosting shallow-implanted nitrogen vacancy (NV) centers. By optimization
based on simulations and precise experimental control of the geometry
of these pillar-shaped nanowaveguides, we achieve a net photon flux
up to ∼1.7 × 10<sup>6</sup> s<sup>–1</sup>. This
presents the brightest monolithic bulk diamond structure based on
single NV centers so far. We observe no impact on excited state lifetime
and electronic spin dephasing time (<i>T</i><sub>2</sub>) due to the nanofabrication process. Possessing such high brightness
with low background in addition to preserved spin quality, this geometry
can improve the current nanomagnetometry sensitivity ∼5 times.
In addition, it facilitates a wide range of diamond defects-based
magnetometry applications. As a demonstration, we measure the temperature
dependency of <i>T</i><sub>1</sub> relaxation time of a
single shallow NV center electronic spin. We observe the two-phonon
Raman process to be negligible in comparison to the dominant two-phonon
Orbach process