Identity Test of Single NV$^-$ Centers in Diamond at Hz-Precision Level

TL;DR

This study demonstrates that negatively charged nitrogen-vacancy centers in diamond can be measured with Hz-level precision, revealing their near-identical nature under ambient conditions and enabling potential applications in atomic-like clocks.

Contribution

The paper introduces a method to measure NV$^-$ centers with Hz-precision, significantly improving parameter accuracy and revealing their near-identical properties in ambient conditions.

Findings

NV$^-$ centers are identical at Hz-precision in ambient conditions.

The $^{14}$N quadrupole coupling parameter is measured with nearly four orders of magnitude higher precision.

Lattice strain can destroy the identity of NV$^-$ centers by tens of Hz.

Abstract

Atomic-like defects in solids are not considered to be identical owing to the imperfections of host lattice. Here, we found that even under ambient conditions, negatively charged nitrogen-vacancy (NV$^-$) centers in diamond could still manifest identical at Hz-precision level, corresponding to a 10$^{-7}$-level relative precision, while the lattice strain can destroy the identity by tens of Hz. All parameters involved in the NV$^-$-$^{14}$N Hamiltonian are determined by formulating six nuclear frequencies at 10-mHz-level precision and measuring them at Hz-level precision. The most precisely measured parameter, the $^{14}$N quadrupole coupling $P$, is given by -4945754.9(8) Hz, whose precision is improved by nearly four orders of magnitude compared with previous measurements. We offer an approach for performing precision measurements in solids and deepening our understandings of NV centers as well as other solid-state defects. Besides, these high-precision results imply a potential application of a robust and integrated atomic-like clock based on ensemble NV centers.