Double-quantum spin-relaxation limits to coherence of near-surface nitrogen-vacancy centers

TL;DR

This study investigates the relaxation mechanisms of near-surface nitrogen-vacancy centers in diamond, revealing that electric field noise-driven double-quantum relaxation limits their coherence, and introduces a new noise spectroscopy method.

Contribution

It provides a detailed analysis of the relaxation processes in NV centers, highlighting the dominance of electric field noise and presenting a novel technique for noise spectrum differentiation.

Findings

Double-quantum relaxation via electric field noise dominates at low magnetic fields.

A new noise spectroscopy technique differentiates electric and magnetic field noise spectra.

Electric field noise sets a fundamental limit on NV center coherence near surfaces.

Abstract

We probe the relaxation dynamics of the full three-level spin system of near-surface nitrogen-vacancy (NV) centers in diamond to define a $T_{1}$ relaxation time that helps resolve the $T_{2} \leq 2T_{1}$ coherence limit of the NV's subset qubit superpositions. We find that double-quantum spin relaxation via electric field noise dominates $T_{1}$ of near-surface NVs at low applied magnetic fields. Furthermore, we differentiate $1/f^{\alpha}$ spectra of electric and magnetic field noise using a novel noise-spectroscopy technique, with broad applications in probing surface-induced decoherence at material interfaces.