Geometric estimation of NV charge-state contributions from a low-dimensional spectral representation
Abstract
Nitrogen-vacancy (NV) centers in diamond exist in neutral (NV0) and negatively charged (NV-) states, and quantifying their respective photoluminescence (PL) contributions is important for charge-state-based measurements. Existing methods either require additional experimental control or may suffer from limited physical identifiability. Here, we introduce a geometric method for determining NV charge-state contributions from PL spectra acquired at different excitation intensities. Each spectrum is mapped into a low-dimensional space through broadband spectral weighting, where changes in the relative NV0 and NV- contributions trace a one-dimensional trajectory. Zero-phonon-line (ZPL) information from two spectra physically calibrates this trajectory, enabling the NV-PL contribution to be determined by geometric projection. Measurements on two bulk single-crystal diamond samples yielded NV- contributions in close agreement with those obtained using an independent dual-excitation reference-spectrum method, with root-mean-square errors of 1.11 and 0.31 percentage points. Under additive spectral noise, the proposed method exhibited more than an order of magnitude less variation than a ZPL-only method. Fisher-information analysis further showed that the three-dimensional CIE XYZ representation retained approximately 81% of the information about the NV- contribution available in the full spectrum. These results establish a physically calibrated approach to low-dimensional spectral estimation that combines reduced experimental overhead with robust parameter estimation and provides a general framework for spectral sensing governed by a small number of physical degrees of freedom.
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BibTeX
@misc{yamakawa2026geometric,
title = {{Geometric estimation of NV charge-state contributions from a low-dimensional spectral representation}},
author = {Yuto Yamakawa and Keisuke Oshimi and Keigo Arai},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38739},
eprint = {2609.38739},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38739},
}
RIS
TY - UNPB
TI - Geometric estimation of NV charge-state contributions from a low-dimensional spectral representation
AU - Yuto Yamakawa
AU - Keisuke Oshimi
AU - Keigo Arai
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.38739
UR - https://arxiv.org/abs/2609.38739
AB - Nitrogen-vacancy (NV) centers in diamond exist in neutral (NV0) and negatively charged (NV-) states, and quantifying their respective photoluminescence (PL) contributions is important for charge-state-based measurements. Existing methods either require additional experimental control or may suffer from limited physical identifiability. Here, we introduce a geometric method for determining NV charge-state contributions from PL spectra acquired at different excitation intensities. Each spectrum is mapped into a low-dimensional space through broadband spectral weighting, where changes in the relative NV0 and NV- contributions trace a one-dimensional trajectory. Zero-phonon-line (ZPL) information from two spectra physically calibrates this trajectory, enabling the NV-PL contribution to be determined by geometric projection. Measurements on two bulk single-crystal diamond samples yielded NV- contributions in close agreement with those obtained using an independent dual-excitation reference-spectrum method, with root-mean-square errors of 1.11 and 0.31 percentage points. Under additive spectral noise, the proposed method exhibited more than an order of magnitude less variation than a ZPL-only method. Fisher-information analysis further showed that the three-dimensional CIE XYZ representation retained approximately 81% of the information about the NV- contribution available in the full spectrum. These results establish a physically calibrated approach to low-dimensional spectral estimation that combines reduced experimental overhead with robust parameter estimation and provides a general framework for spectral sensing governed by a small number of physical degrees of freedom.
ER -