Can ultraprecision polishing techniques improve the coherence times of nitrogen-vacancy centers in diamond?

TL;DR

This study examines whether ultraprecision polishing can enhance the coherence times of near-surface nitrogen-vacancy centers in diamond, finding that coherence times are surprisingly unaffected by surface roughness.

Contribution

It compares various polishing techniques, substrate sources, and surface terminations to assess their impact on NV center coherence times.

Findings

Coherence times are largely independent of surface roughness.

Surface treatments at 520°C do not significantly alter coherence times.

Different polishing and surface termination methods show minimal effect on NV coherence.

Abstract

We investigate the correlation between surface roughness and corresponding $T_2$ times of nearsurface nitrogen-vacancy centers (~7 nm/ 5 keV implantation energy) in diamond. For this purpose we compare five different polishing techniques, including both purely mechanical as well as chemical mechanical approaches, two different substrate sources (Diam2tec and Element Six) and two different surface terminations (O- and H-termination) during nitrogen-vacancy forming. All coherence times are measured and compared before and after an oxygen surface treatment at 520 {\deg}C. We find that the coherence times of shallow nitrogen-vacancy centers are surprisingly independent of surface roughness.