Spectrally stable nitrogen-vacancy centers in diamond formed by carbon implantation into thin microstructures

TL;DR

This study shows that carbon ion implantation creates spectrally stable nitrogen-vacancy centers in diamond microstructures, maintaining narrow optical linewidths and low noise, which is promising for quantum sensing and networking applications.

Contribution

It demonstrates that carbon ion implantation is an effective alternative to nitrogen implantation for creating coherent NV centers in thin diamond structures.

Findings

Median NV linewidth of 150 MHz in structures thinner than 5 μm

No increase in linewidths down to 1.9 μm thickness

Carbon implantation yields NV densities comparable to nitrogen implantation

Abstract

The nitrogen-vacancy center (NV) in diamond, with its exceptional spin coherence and convenience in optical spin initialization and readout, is increasingly used both as a quantum sensor and as a building block for quantum networks. Employing photonic structures for maximizing the photon collection efficiency in these applications typically leads to broadened optical linewidths for the emitters, which are commonly created via nitrogen ion implantation. With studies showing that only native nitrogen atoms contribute to optically coherent NVs, a natural conclusion is to either avoid implantation completely, or substitute nitrogen implantation by an alternative approach to vacancy creation. Here, we demonstrate that implantation of carbon ions yields a comparable density of NVs as implantation of nitrogen ions, and that it results in NV populations with narrow optical linewidths and low charge-noise levels even in thin diamond microstructures. We measure a median NV linewidth of 150 MHz for structures thinner than 5 $\mu$m, with no trend of increasing linewidths down to the thinnest measured structure of 1.9 $\mu$m. We propose a modified NV creation procedure in which the implantation is carried out after instead of before the diamond fabrication processes, and confirm our results in multiple samples implanted with different ion energies and fluences.