Surface coating with oxide layers to enhance the spin properties of shallow NV centers in diamond

TL;DR

This paper demonstrates that depositing titanium oxide layers on diamond surfaces enhances the spin relaxation and evolution times of shallow NV centers, improving their stability and coherence without surface damage.

Contribution

It introduces a surface coating method using ALD to improve NV center spin properties, a novel approach for quantum device packaging.

Findings

Relaxation time increased by 2 to 3.5 times

Charge states of NV centers stabilized

Coherence time remained nearly unchanged

Abstract

We present an enhancement of spin properties of the shallow (<5nm) NV centers by using ALD to deposit titanium oxide layer on the diamond surface. With the oxide layer of an appropriate thickness, increases about 2 up to 3.5 times of both relaxation time and evolution time were achieved and the shallow NV center charge states stabilized as well. Moreover, the coherence time kept almost unchanged. This surface coating technique could produce a protective coating layer of controllable thickness without any damages to the solid quantum system surface, making it possible to prolong T1 time and T2* time, which would be a possible approach to the further packaging technique for the applicating solid quantum devices.