Blueprint for Diamond Magnetometry: Unraveling Quantum Dephasing of Nitrogen-Vacancy Center Ensembles in Diamond

TL;DR

This paper systematically analyzes the quantum dephasing mechanisms in nitrogen-vacancy (NV) center ensembles in diamond, providing insights to enhance magnetic sensing sensitivity by understanding and mitigating dephasing sources.

Contribution

It introduces a measurement method to quantify and analyze various dephasing sources in NV ensembles, guiding improvements in quantum sensing performance.

Findings

NV-NV interactions significantly affect dephasing

Strain and electric fields contribute to dephasing

Strategies proposed to improve magnetic sensitivity

Abstract

Diamonds with nitrogen-vacancy (NV) center ensembles are one of the most promising solid-state quantum platforms for various sensing applications. The combination of a long spin dephasing time ($T_2^*$) and a high NV center concentration is crucial for pushing the sensitivity limits. In this work, we propose a systematic measurement approach to quantify the electron spin dephasing in NV center ensembles and analyze the contributions of various sources to the dephasing time, including NV-NV interactions, strain and electric field distributions, $^{13}$C nuclear spins, and P1 electron spins. Our method is validated using a series of high-performance diamond samples, providing a comprehensive understanding of dephasing mechanisms and revealing correlations between NV concentration and different dephasing sources. Based on these insights, we further evaluate and propose strategies to improve the achievable sensitivity limits for DC magnetic field measurements.