# Optical coherence of diamond nitrogen-vacancy centers formed by ion implantation and annealing

## TL;DR

This study investigates how the optical coherence of nitrogen-vacancy centers in diamond depends on their nitrogen source, revealing that naturally-occurring nitrogen yields better coherence than implanted nitrogen, impacting quantum technology applications.

## Contribution

The paper provides direct experimental evidence linking NV center optical coherence to nitrogen origin, highlighting the effects of implantation versus natural incorporation.

## Key findings

- Naturally-occurring $^{14}$N NV centers have narrow linewidths (<500 MHz).
- Implanted $^{15}$N NV centers show broader linewidths (>1 GHz).
- Poor coherence from implanted nitrogen is not due to intrinsic diamond properties.

## Abstract

The advancement of quantum optical science and technology with solid-state emitters such as nitrogen-vacancy (NV) centers in diamond critically relies on the coherence of the emitters' optical transitions. A widely employed strategy to create NV centers at precisely controlled locations is nitrogen ion implantation followed by a high-temperature annealing process. We report on experimental data directly correlating the NV center optical coherence to the origin of the nitrogen atom. These studies reveal low-strain, narrow-optical-linewidth ($<500$ MHz) NV centers formed from naturally-occurring $^{14}$N atoms. In contrast, NV centers formed from implanted $^{15}$N atoms exhibit significantly broadened optical transitions ($>1$ GHz) and higher strain. The data show that the poor optical coherence of the NV centers formed from implanted nitrogen is not due to an intrinsic effect related to the diamond or isotope. These results have immediate implications for the positioning accuracy of current NV center creation protocols and point to the need to further investigate the influence of lattice damage on the coherence of NV centers from implanted ions.